Class 


The  D.  Van  Nostrand  Company 

intend  this  booh  to  be  sold  to  the  Public 
at  the  advertised  price,  and  supply  it  to 
the  Trade  on  terms  which  will  not  allow 
of  discount. 


LIBRARY 

OF  THE 

UNIVERSITY  OF  CALIFORNIA. 

Class 


Generating  Room  of  59th  Street  Power  Plant  of  the  Interborough  Rapid  Transit  Co. 

(Subway)  New  York. 

Largest  reciprocating  Engine  Plant  in  the  world.  ,  Present  installation  consists  of  nine  7500  II. P. 
Engines  and  three  1250  K.W.  Turbo-Generators.  Ultimate  maximum  capacity  between  130,000  and 
150,000  II. P. 


STEAM-ELECTRIC  POWER 

PLANTS 

sl  Practical  Treatise  on  the  Design  of  Central 

Light  and  Power  Stations  and  their 

Economical   Construction 

and  Operation 


BY 

FRANK   KOESTER 
•  i 

CONSULTING    AND    DESIGNING    ENGINEER 

MEMBER    VEREIN    DEUTSCHER    INGENIEURE.    ASSOCIATE    MEMBER 
AMERICAN    INSTITUTE    ELECTRICAL    ENGINEERS 


OF    THE 

UNIVERSITY 

OF 


NEW   YORK 

D.  VAN    NOSTRAND  COMPANY 

23   MURRAY   AND   27   WARREN   STS. 
1908 


COPYRIGHT,   1908 

BY 

D.  VAN   NOSTRAND    COMPANY 


ALSO  ENTERED  AT  STATIONERS'  HALL  COURT,  LONDON,  ENGLAND 

All  Rights  Reserved 


KOUKKT    DRI'MMOMJ    COMPANY,    1'KIN'TKRS,    NK\V    YORK 


PREFACE. 


IT  is  the  aim  of  the  Author,  in  this  volume,  to  give  such  information  in  regard  to 
modern  power  plant  practice  as  is  essential  to  the  engineer  in  designing  steam-elec- 
tric power  plants.  No  attempt  has  been  made  to  treat  the  design  of  machinery,  such 
as  boilers,  turbines,  generators,  etc.,  since  excellent  separate  works  on  the  subject 
already  exist,  and  it  would  be  impossible  to  combine  so  much  in  a  single  volume. 

This  book  is  compiled  to  a  great  extent  from  the  experience  in  America  and  Europe, 
of  the  Author,  who  has  been  closely  identified  with  the  design  of  plants  for  Europe, 
Asia,  Africa,  Central  and  South  America,  as  well  as  the  construction  and  operation  of 
plants  of  100  to  24,000  K.W.  normal  capacity.  For  the  purpose  of  studying  American 
power  plants  on  a  broader  scale,  their  practical  method  of  design,  construction  and 
operation,  he  has  been  identified  in  America  for  a  number  of  years  with  some  of  the 
largest  and  most  prominent  plants  in  the  country,  varying  from  500  to  60,000  K.W. 
normal  capacity. 

For  a  number  of  years  he  has  contributed  to  the  technical  press  and  to  technical 
societies  on  both  sides  of  the  Atlantic  articles  on  the  design  of  power  plants,  and  is 
indebted  to  the  following  Journals  for  permission  to  embody  a  few  of  these  articles 
which  have,  however,  been  partly  rewritten,  considerably  extended,  or  revised : 

Electrical  Review  (N.Y.)  for  the  chapter  "The  Design  of  Small  Power  Plants", 
and  "The  Vienna  Power  Plants";  Power  for  the  article  "Coal  Handling  System", 
and  "The  St.  Denis  Power  Plant,  Paris";  Street  Railway  Review  for  the  article  "High 
Pressure  Piping",  and  "Superheaters";  Zeitschrift  des  Vereines  deutscher  Ingenieure, 
for  the  article  "The  59th  Street  Power  Plant,  New  York". 

The  Author  is  of  the  opinion  that  a  good  illustration  may  tell  more  than  a  long  dis- 
cussion, and  has,  therefore,  added  numerous  cuts,  many  of  which  have  accompanied 
his  articles.  For  these  he  is  indebted  to  various  engineering  companies,  manufac- 
turers, and  to  the  following  Journals,  besides  those  already  mentioned:  Street  Rail- 
way Journal,  Electrical  World,  Engineering  Record,  Engineering  News,  The  Engineer, 
Engineering  Magazine,  Western  Electrician,  The  Tramway  and  Railway  World,  Jour- 
nal of  the  Institution  of  Electrical  Engineers  (London),  Journal  le  Genie  Civil,  Schweizer 
Bauzeitung,  Zeitschrift  des  Oesterr.  Ingenieur  und  Architekten  Vereines,  Elektrische 
Krajtbetriebe  und  Bahnen,  etc. 

THE  AUTHOR. 

NEW  YORK  CITY,  January,  1908. 


196446 


CONTENTS. 


CHAPTER    I. 

PAGES 

GENERAL  REMARKS:  Practical  Problems;  Efficiency;  Cost  of  Plants 1-8 


CHAPTER    II. 

LOCATION:  Introductory;  Current  Distribution;  Coal  Supply;  Water  Supply;  Space  for 

Future  Extension;  Cost  of  Land;  Character  of  Soil;  Local  Labor  Supply 9-12 

GENERAL  LAYOUT:   General   Consideration;   Complete  Unit  System;  Boiler  House; 

Engine  House;  Switching  Room;  Coal  Storage  Plant;  Auxiliary  Buildings 12-27 

COAL  STORAGE:  Introductory;  Exposed  Coal  Pile;  Spontaneous  Combustion;  Character 
of  Storage  Plants;  Description  of  Various  Storage  Plants;  Comparison  of  Various 
Systems;  Overhead  Bunkers;  Bunker  Fires 27-38 

CONDENSER  WATER  SUPPLY:  Inlet  and  Outlet  Tunnels;  Screen  Chamber;  Shut-off 
Gates;  Area  of  Tunnel  and  Screens;  Arrangement  of  Inlet  and  Outlet  Tunnels; 
Scarcity  of  Condenser  Water 38-40 


CHAPTER    III. 

EXCAVATION  AND  FOUNDATION  :  Selection  of  Site;  Test  Holes;  Character  of  Soil;  Concrete 
Mat  Construction;  Concrete  Piles;  Test  Piles;  Bearing  Power  of  Soil;  Weight  of 
Masonry;  Size  of  Foundations;  Location  of  Foundations;  Concrete  Forms;  Concrete 
Mixture;  Grouting;  Waterproofing 41-48 

BUILDING:  Material;  Floors;  Pipe  Trenches;  Switchboard  Gallery;  Walls;  Windows; 
Doors;  Ventilators;  Stairways  and  Elevators;  Toilets  and  Plumbing;  Heating  and 
Ventilation;  Roof;  Leaders 48-58 

STRUCTURAL  STEEL:  Roof  Construction;  Crane  Runway;  Building  Material;  Framing; 
Type  of  Columns;  Floor  Loads;  Fiber  Stresses;  Expansion  Joints;  Column  Base; 
Floor  Beams,  etc.;  Structural  Steel  of  Recent  Plants;  Workmanship;  Inspection; 
Painting;  Insulation  of  Steel  Frame;  Character  of  Steel 58-69 

ARCHITECTURAL  FEATURES:  Review;  Windows  and  Doors;  Crane;  Walls;  Floors;  Pipe 
Trenches;  Galleries;  Switchboard;  Boiler  Room;  Removal  of  Ashes;  Coal  Storage 
Plant;  Chimneys;  Conclusion 69-84 

V 


vi  CONTENTS. 


CHAPTER    IV. 

PAGES 

BOILERS:  Type  of  Boilers;  Safety;  Simplicity;  Durability;  Water  Circulation;  Heat- 
ing Surface;  Grate  Surface;  Efficiency;  Setting;  Trimmings;  Size;  Babcock  & 
Wilcox  Boilers;  Stirling  Boilers;  Wickes  Boilers;  Foreign  Types  of  Boilers; 
Conclusion  85-99 

MECHANICAL  STOKERS  AND  GRATES:  Advantages  and  Disadvantages;  Systems  of 

Stokers;  Grates 99-104 

COAL:    Introductory;  Heat  Value;  Character  of  Coal;  Analysis 104-113 

COMBUSTION:    Combustion;  Air  Required;  CO 2  Recorder 113-119 

DRAFT:  Meaning;  Production;  Loss;  Chimney  Draft;  Mechanical  Draft;  Forced  Draft; 

Induced  Draft;  Steam  Blower 119-130 

SMOKE  FLUES:  Character;  Shape;  Size;  Expansion  Joints;  Leakage;  Doors;  Dampers; 

Automatic  Regulator 131-136 

CHIMNEYS:  Character;  Material:  Radial  Brick;  Reinforced  Concrete;  Steel  Chimneys; 
Guyed  Chimneys;  Self-Supporting  Chimneys;  Lining;  Baffle  Wall;  Ladders; 
Lightning  Arresters 136-147 

BOILER  FEED  WATER:  Pure  Water;  Impure  Water;  Boiler  Corrosion;  Mud;  Boiler 

Scale;  Scum;  Dervaux-Reisert  Purifier ;  Storage 147-154 

FEED- WATER  HEATERS:  Open  Heater;  Closed  Heater;  Economizer;  Percentage  of 

Gain * 154-163 

SUPERHEATERS:  Classification;  Material;  Cross-Section;  Circulation  of  Steam  and 

Flow  of  Gases;  Controlling  Temperature;  Velocity  of  Steam;  Size;  Types  .    .    .    163-175 

SUPERHEATED  STEAM:   Saturated  Steam;  Superheated  Steam 175-179 

CHAPTER   V. 

PIPING,  HIGH-PRESSURE:  Introductory;  Size  of  Pipes;  General  Consideration;  System 
of  Piping;  Expansion;  Anchors;  Supports  and  Hangers;  Fittings;  Flanges;  Valves; 
Drip  System;  Pipe  Covering;  Boiler  Feed  Piping;  Boiler  Blow-Off  Piping  ....  180-217 

LOW-PRESSURE  PIPING:  Size  of  Exhaust  Pipes;  Material;  Fittings;  Drips;  Circulating 

Water  Piping;  Vacuum  and  Hot  Well  Piping;  Covering 217-221 

CHAPTER   VI. 

PRIME  MOVERS :  Comparison  of  Engine  and  Turbine;  Size  of  Prime  Movers 222-225 

RECIPROCATING  ENGINES:  Classification;  Valve  Mechanism;  Simple  Engines;  Com- 
pound Engines;  Triple  Expansion  Engines;  Quadruple  Expansion  Engines  .  .  .  225-231 


CONTENTS.  vu 

PAGES 
TURBINES:  Classification;  Single  Impulse  Turbine;  Compound  Impulse  Turbine; 

Reaction  Turbine 231-240 

CONDENSERS:  Principle;  Classification;  Application;  Condenser  Water  Required;  Jet 
Condenser;  Surface  Condenser;  Central  Condenser;  Vacuum  Breaker;  Cooling 
Towers;  Cooling  Ponds 240-261 

PUMPING  MACHINERY:  Steam  or  Electric  Drive;  Steam  Consumption  of  Auxiliaries; 
Circulating  Pumps;  Air  Pumps;  Hot- Well  Pumps;  House  Pumps;  Boiler  Feed 
Pumps;  Oil  Pumps;  Fire  Pumps 262-268 

OILING  SYSTEM:  Oil  Required;  Filtering  Tanks;  Oil  Pumps;  Supply  Tanks;  Oil  Piping.  268-273 


CHAPTER    VII. 

ELECTRICAL  EQUIPMENT:  Introductory;  Generators;  Exciters;  Generator  Leads; 
Switching  Room;  Wiring  Diagram;  Bus-Bar  Chambers;  Oil  Switches;  Switch- 
board; Storage  Battery  274-291 


CHAPTER   VIII. 

THE  DESIGN  OF  SMALL  POWER  PLANTS:  Introductory;  Type  and  Size  of  Plant;  Loca- 
tion of  Plant ;  Foundation  Work;  Superstructure ;  Masonry  Work,  etc. ;  Sanitary  and 
Architectural  Features;  Coal  and  Ash  Handling  Systems;  Boilers,  etc.;  Boiler 
Feed- Water  Supply;  Smoke  Flues  and  Chimney;  Steam  Piping;  Turbines  and 
Generators;  Condenser  Plant;  Exciters  and  Air  Compressor;  Switchboard  and 
Wiring  System;  Conclusion ."....  292-317 


CHAPTER    IX. 

TESTING  POWER  PLANTS:  General  Considerations;  Preparation  of  Boiler  Tests;  Method 
of  Boiler  Tests;  Reports  of  Boiler  Tests;  Method  of  Testing  Prime  Movers;  Test 
of  an  Engine;  Parsons  Turbine  Tests;  Generator  Tests 3Z8~335 


CHAPTER   X. 

DESCRIPTIVE  DISCUSSION  OF  TYPICAL  AMERICAN  AND  EUROPEAN  LIGHT  AND  POWER 
PLANTS: 

St.  Denis  Plant,  Paris 336-349 

Fifty-Ninth  Street  Plant,  New  York 349-361 

Chelsea  Plant,  London      361-370 

Fisk  Street  Plant,  Chicago 371-381 

Twin  Municipal  Plant,  Vienna 381-397 


viii  CONTENTS. 

CHAPTER    XI. 

PAGES 

PRINCIPAL  DIMENSIONS,  DATA  AND  ILLUSTRATIONS  or  RECENTLY  CONSTRUCTED 
LIGHT  AND  POWER  PLANTS: 

Potomac  Plant,  Washington,  D.C 399 

L  Street  Plant,  Boston       400-405 

Fifty-Ninth  Street  Plant,  New  York 406-407 

Long  Island  City  Plant 408-415 

Chelsea  Plant,  London      :    .    . 416 

Berlin  Plants,  Germany 417-422 

St.  Denis  Plant,  Paris 423 

New  York  Central  Plants,  New  York 424-432 

D.  &  H.  Co.,  Mechanicville,  New  York 433 

Commerce  St.  Plant,  Milwaukee 434-435 

Boiler  Heating  Surface  per  K.W.  Capacity 436 

Comparison  of  Area  and  Volume  per  K.W.  Capacity 436 

Quincy  (Mass.)  Plant 437 

APPENDIX. 

Series  of  Tables  of  the  Metric  and  English  Weights  and  Measures 437-447 

Index 449-455 


LIST    OF    ILLUSTRATIONS. 


ARRANGEMENT  OF  POWER  PLANTS. 
PLANS. 

PACK 

Belfast,  Ireland,  Municipal 114 

Carville,  Newcastle  upon  Tyne 24 

Chelsea,  London 362,  364 

Commerce  Street,  Milwaukee .     433 

Engine  and  Boiler  Room .     13,  18 

59th  Street,  New  York 352 

Fisk  Street,  Chicago 372,  375 

L  Street,  Boston 401 

Moabit,  Berlin 420 

Oberspree,  Berlin .     418 

Port  Morris,  New  York 427 

Portsmouth,  Ohio 8 

Quincy,  Massachusetts 436 

Small  Plant 297 

St.  Denis,  Paris .     337 

Turbine  and  Boiler  Room 15,  16 

Twin  Municipal,  Vienna 382,  388 

CROSS- SECTIONS. 

Belfast,  Ireland,  Municipal ,  118 

Chelsea,  London 364 

Commerce  Street,  Milwaukee 434 

Engine  and  Boiler  Room 18 

59th  Street,  New  York 1    ...  352 

Fisk  Street,  Chicago 375 

L  Street,  Boston 403 

Long  Island  City 408 

Port  Morris,  New  York 425 

Portsmouth,  Ohio 8 

Quincy,  Massachusetts 436 

Small  Plant 302 

St.  Denis,  Paris 338 

Trebbiner  Street,  Berlin 422 

Turbine  and  Boiler  Room 19,  20 

Twin  Municipal,  Vienna 386 

Yonkers,  New  York 426 

ix 


x  LIST    OF    ILLUSTRATIONS. 

BUILDINGS. 
EXTERIOR  VIEWS. 

PAGE 

Delaware  Avenue,  Philadelphia 48 

Dresden,  Germany 74 

59th  Street,  New  York 350 

Fisk  Street,  Chicago 49,  372 

Greenwich,  England 50 

Grove  Road,  London 70 

Hanover,  Germany 73 

L  Street,  Boston 56 

Mechanicville,  New  York 54 

Moabit,  Berlin 419 

Oberspree,  Berlin „    .  417 

St.  Denis,  Paris 337 

Seventy-Fourth  Street,  New  York 57 

Small  Plant 293 

Twin  Municipal,  Vienna 382 

Waterside  No.  2,  New  York 91 

STRUCTURAL  STEEL. 

Delaware  Avenue,  Philadelphia 55 

G.  E.  Co.,  Schenectady,  New  York 63 

Waterside  No.  2,  New  York 51 

Williamsburg,  Brooklyn 65 

Columns,  Types  of 62 

Roof  Trusses,  Types  of 60 

FOUNDATIONS,  ETC. 

Concrete  and  Wooden  Piles 45 

Mat  Construction,  Long  Island  City 44 

CHIMNEYS. 

Brick,  Radial 137 

Concrete,  Reinforced 141 

Dresden,  Architectural  Features 74 

Munich,  Architectural  Features 83 

Steel,  Long  Island  City 144 

Steel,  Self- Supporting 143 

COAL  AND  ASH  HANDLING  SYSTEMS. 

Fifty-Ninth  Street,  New  York 353 

Long  Island  City 409 

L  Street,  Boston 31 

Moabit,  Berlin       421 

Rhode  Island,  Providence 29 

Scheme 28 


LIST    OF    ILLUSTRATIONS.  xi 

COAL  AND  ASH  HANDLING  SYSTEMS  —  Continued.  PACIH 

Shadyside,  New  York      32,  33 

St.  Denis,  Paris 339 

Twin  Municipal,  Vienna 383 

Williamsburg,  Brooklyn 34,  35 

Willisden,  London 30 

EQUIPMENT  OF  BOILER  ROOMS. 
BOILER  ROOMS. 

Fisk  Street,  Chicago 373,  376 

Frankfurt  on  the  Main,  Germany 8r 

Hamburg,  Germany 85 

L  Street,  Boston 400,  402,  404 

Long  Island  City 410,  412 

Port  Morris,  New  York 429 

Reading  R.  R.,  Philadelphia 98 

St.  Denis,  Paris 343 

Stuart  Street,  Manchester 102 

Twin  Municipal,  Vienna 380 

BOILERS,  STOKERS,  FLUES. 

Babcock  and  Wilcox  Boiler 91 

Fifty-Ninth  Street,  New  York 98 

Hornby,  Horizontal  Boiler 89 

Hornby,  Upright  Boiler 90 

Lancashire  Boiler      96. 

Lindhaus  Boiler 97 

St.  Denis,  Paris 339 

Steel  Work  and  Setting 57 

Stirling  Boiler 94 

Twin  Municipal,  Vienna 390 

Stokers,  Green 101 

Jones 103 

McClave,  Grate 103 

Roney 101 

Roney,  Pressure  Record 102 

"        Roney,  Setting 104 

Smoke  Flues,  Expansion  Joints 132 

Fisk  Street,  Chicago 374 

"        Damper  Regulator 134 

"        Damper  Regulator,  Pressure  Record 135 

FEED-WATER  HEATERS,  PURIFIERS,  ETC. 

Economizer,  Green 160 

Economizer  Plant,  Union  R.  R.  Co.,  Providence,  R.I 160 

Closed  Heater,  Arrangement  of      159 

Closed  Heater,  Otis 158 

Open  Heater,  Arrangement  of 157 


xii  LIST    OF    ILLUSTRATIONS. 

FEED- WATER  HEATERS,  PURIFIERS,  ETC.  —  Continued.  PAGB 

Open  Heater,  Cochrane       156 

Open  Heater,  Stillwell 155 

Purifier,  Dervaux-Reisert 153 

Purifier  Plant,  Syracuse,  New  York 153 

Purifier  Plant,  Twin  Municipal,  Vienna 391 

SUPERHEATERS. 

Flow  of  Gases  and  Steam 166 

Forms  of  Superheaters 165 

Section  of  Tubes 161 

Types,  Babcock  &  Wilcox ....  98 

"       Buettner 160 

"       Cruse i?8 

"       Dingier *63 

"       Forster 9? 

"       Goehring *77 

"       Heizmann J75 

"       Hering 97 

"       Schwoerer J75 

"       Stirling      94 

Watkinson i?4 

Volume  of  Superheated  Steam 176,  i?7>  T78 

PIPING,  OIL  FILTERS,  ETC. 
PIPES,  VALVES,  FITTINGS,  ETC. 

Anchor J9° 

Anchor  Location I9° 

Anchor  Cast  Steel l88 

Bracket  with  Adjustable  Rollers I91 

Bracket  for  Pipe  Riser     ....  iQ3 

Bends,  Expansion I94 

Exhaust  Head 2l8 

Expansion  Joint I9S 

Fittings,  Cast      X96 

Fittings,  High  Pressure X97 

Fittings,  Welded  Steel,  Loose  Flanges X98 

Flanges,  Drilling,  High  Pressure    .    . 

Flanges,  German,  High  Pressure  ...                                                        .   202,  203,  204 

Flanges,  Fifty-Ninth  Street,  New  York,  High  Pressure    ...  201 

Header  System,  Double 

Header  System,  Ring   .    . 

Header  System,  Single     ...  l84 

Manifold,  Welded  Steel   .    . 

Piping,  Fifty-Ninth  Street,  New  York  .    .                                                        ....  187 

Piping,  Yonkers,  New  York 43 l 

Piping,  Port  Morris,  New  York 43° 


LIST    OF    ILLUSTRATIONS.  xiii 

PIPES,  VALVES,  FITTINGS,  ETC.  —  Continued.  PAGB 

Piping,  Small  Plant 304 

Relief  Valve 217 

Separator,  Cochrane 210 

Separator,  Stratton 209 

Slip  Joint 195 

Support,  Balanced,  for  Riser 193 

Support,  Anchors,  Wall  Sleeves 192 

Swivelling  Joint 189 

Traps,  Steam 211,  212 

Valve,  Back  Pressure 217 

"      Blow-off      216 

"      Blow-off  Cock 216 

"      Check,  Boiler  Feed 215 

"      Closing,  Automatic 208 

"      Foot  and  Screen 220 

"      Gate,  Taper  Seat 205 

"      Globe  German 206 

"      Non-Return 207 

"      Reducing,  Anderson 209 

Water  Meter,  Pipe  Connection 221 

OIL  FILTERS  AND  SEPARATORS. 

Austin  Vacuum  Separator 158 

Baker  Separator 250 

Burt  Filter 269 

Filter  Tank 271 

Oil  Piping  of  Curtis  Turbine      272 

Turner  Filter 270 

Utility  Oil  Extractor 218 

EQUIPMENT  OF  GENERATING  ROOMS. 
GENERATING  ROOMS. 

Charlottenburg,  Germany 79 

Chelsea,  London 366 

Fifty-Ninth  Street,  New  York frontispiece 

Fisk  Street,  Chicago 377 

Harland   &  Wolff,  Belfast 77 

L  Street,  Boston 75 

Long  Island  City      411 

Moabit,  Berlin       419 

Oberspree,  Berlin      417 

Port  Morris,  New  York 424 

St.  Denis,  Paris .    339,  343 

Twin  Municipal,  Vienna 393 


xiv  LIST    OF    ILLUSTRATIONS. 

RECIPROCATING  ENGINES. 

PAGE 

Right  and  Left  Hand  Engines 226 

Engines  and  Turbines,  Comparison 223 

Compound  Engine,  7500  H.P 228 

Fifty-Ninth  Street  Plant,  New  York 358 

Quadruple  Expansion  Engine,  Six  Cylinder 231 

Single  Cylinder  Engine 227 

Triple  Expansion  Engine,  Four  Cylinder 230 

TURBINES,  ETC. 

Comparison  of  Turbine  and  Reciprocating  Engine 233 

Brown,  Boveri-Parsons  Turbine 233 

Curtis  Turbine 239 

De  Laval  Turbine 232 

Rateau  Turbine 236 

Westinghouse-Parsons  Turbine 237 

Turbine  Test  Curve 329>  33°>  332 

Essen,  Germany,  65OO-K.W.  Parsons 239 

Fisk  Street,  Chicago,  gooo-K.W.  Curtis 378 

L  Street,  Boston,  Turbine  Unit  with  Auxiliaries 400-405 

Neasden,  London      238 

St.  Denis,  Paris,  5ooo-K.W.  Turbo-Generator 344 

St.  Denis,  Paris,  Turbine  Unit  with  Auxiliaries      346 

CONDENSERS,  PUMPS,  COOLING  PLANTS,  ETC. 

Alberger,  Jet  Condenser 245 

Alberger,  Fifty-Ninth  Street,  New  York 246,  247 

Bulkly,  Jet  Condenser 243 

Cooling  Plant 258,  260 

Cooling  Pond 259 

Cooling  Towers,  German 254,  255 

Cooling  Towers,  Alberger 256 

Cooling  Towers,  Worthington 257 

Eductor  Condenser,  Schutte  &  Koerting 261 

Delaware  Avenue,  Philadelphia      248 

Long  Island  City      4M 

Small  Plant 312 

St.  Denis,  Paris 346 

Vacuum  Augmenter      249 

Pumps,  Air .    .  267 

Air,  St.  Denis,  Paris •    •    •  347 

"       Arrangement,  Fifty-Ninth  Street,  New  York                            356 

Centrifugal 267 

"       Motor  Driven      262 

"       Motor  Driven,  Vienna 385 

"       Water  Supply,  Vienna 386 


LIST    OF    ILLUSTRATIONS.  xv 

CONDENSERS,  PUMPS,  COOLING  PLANTS,  ETC.  —  Continued.  PAGE 

Seventy-Fourth  Street,  New  York 241 

Surface  Condenser 251 

Surface  Condenser,  Pinkston,  Glasgow 241 

Surface  Condenser,  Worthington , 253 

Water  Supply  System,  Vienna 385 

Vacuum  Augmenter,  Parsons 249 

Weiss  Dry  Jet  Condenser 242 

Worthington  Jet  Condenser 240 

EQUIPMENT  OF  SWITCHING  ROOMS. 
SWITCHING  ROOMS. 

Carville,  Newcastle  upon  Tyne 281,  282 

Fifty-Ninth  Street,  New  York 280,  285 

Fisk  Street,  Chicago 379,  380 

Long  Island  City 275,  411,  413 

Swiss  Practice 286,  287 

Waterside  No.  2,  New  York      279 

SWITCHBOARDS,  ETC. 

Charlottenburg,  Germany 79 

Fifty-Ninth  Street,  New  York 360 

German,  Type  of  .    . 289 

Hamburg,  Germany 288 

Long  Island  City      413 

Long  Island  City,  Feeder  Cables 276 

Port  Morris,  New  York 432 

St.  Denis,  Paris 348 

Swiss  Practice 286 

Swiss  Practice,  6000  Volts  Apparatus 287 

Swiss  Practice,  27,000  Volts  Apparatus 287 

Twin  Municipal,  Vienna 394,  395 

WIRING  DIAGRAMS. 

Carville,  Newcastle  upon  Tyne 284 

Chelsea,  London 369 

Fifty-Ninth  Street,  New  York 283,  359 

Fisk  Street,  Chicago 379 

Long  Island  City      277,  415 

Port  Morris,  New  York 429 

Small  Plant - 315 

Twin  Municipal,  Vienna 396 


LIST     OF     TABLES. 


PAGE 

Heat  Losses  in  a  Power  Plant  per  Pound  of  Coal 2 

Equivalent  of  Heat  and  Mechanical  Units 4 

Cost  of  Turbine  Plant 6 

Cost  of  Engine  Plant 6 

Cost  per  Unit  generated  of  British  Plants 7 

Safe  Bearing  Power  of  Soil 46 

Weight  of  Masonry 46 

Floor  Load  of  59th'  St.  Plant,  New  York 63 

Structural  Steel  of  Recent  Plants 65 

Boiler  Horse-Power  per  K.W.  Capacity 93 

Heat  Power  of  Coal 106 

Character  of  Coal no 

Analyses  and  Heating  Values  of  American  Coals 114 

Pressure  in  Inches  Equivalent  to  Ounces .  120 

Height  of  Water  Column  due  to  Unbalanced  Pressures  in  Chimneys  100  Feet  High  .  121 

Kent's  Tables  of  Size  of  Chimneys 123 

Christy's  Table  of  Size  of  Chimneys 124 

Chimney  Data  of  Recent  Power  Plants 124 

B.T.U.  carried  off  by  Escaping  Gases 125 

Weight  of  Air,  etc 129 

Velocity  of  Air  created  by  Draft '. 130 

Percentage  of  Saving  for  each  Degree  of  Increase  in  Temperature  of  Feed- Water  Heated   .  161 

Percentage  of  Saving  effected  by  Heating  Feed- Water  from  Initial  to  Final  Temperature    .  162 

Coal  Needed  for  Superheating  Steam 173 

Properties  of  Saturated  and  Superheated  Steam .  179 

Area  of  Circles > 186 

Equation  of  Pipes 180 

Fall  in  Pressure  in  Standard  90°  Bends  Equivalent  to  Straight  Pipes 181 

Dimensions  of  Expansion  Bends 192 

High-Pressure  Fittings 194 

Tensile  Strength  of  Pipe  Material 197 

Drilling  of  Standard  High-Pressure  Flanges,  adopted  in  America      200 

Standard  High-Pressure  Flanges,  adopted  in  Germany 202 

High-Pressure  Flanges,  adopted  for  the  59th  St.  Plant,  New  York 201 

Dimensions  for  High-Pressure  Gate  Valve       205 

Dimensions  for  High-Pressure  Non-return  Valves      207 

Loss  of  Heat  from  Bare  Steam  Pipes 212 

Efficiency  of  Pipe  Covering 215 

Capacity  in  Gallons  per  Minute  discharged  in  Pipes 219 

xvii 


xv»»  LIST    OF    TABLES. 

PAC;B 

Floor  Space  occupied  by  Prime  Movers 224 

Test  of  5000-K.W.  Curtis  Turbine 234,  235 

Steam  Consumption  of  Auxiliaries 263 

Steam  Consumption  of  Pump  of  a  5000- K.W.  Turbine 264 

Test  of  Condenser  Apparatus 265 

Result  of  a  350-H.P.  Boiler  Test 319 

Result  of  a  yoo-H.P.  Boiler  Test 321 

Result  of  a  48o-H.P.  Engine  Test 326 

Results  of  Tests  of  Parsons  Turbines  of  Various  Sizes 327 

Results  of  a  400- K.W.  Parsons  Turbine  Test 328,329,331 

Generator  Tests .    .    333,  334,  335 

Guaranteed  Steam  Consumption  of  55oo-K.W.  Parsons  Turbine,  Chelsea  Plant,  London  .  367 

Test  of  Twin  Municipal  Plant,  Vienna 397 

Dimensions  and  Data,  Potomac  Plant,  Washington,  D.C 399 

Dimensions  and  Data,  59th  St.  Plant,  New  York 406 

Dimensions  and  Data,  Chelsea  Plant,  London 416 

Dimensions  and  Data,  St.  Denis  Plant,  Paris 423 

Dimensions  and  Data,  D.  &  H.  Co.  Plant,  Mechanicville,  New  York 433 

Boiler  Heating  Surface  per  K.W.  Capacity 436 

Area  of  Power  House  per  K.W.  Capacity 436 

Volume  of  Power  House  per  K.W.  Capacity 436 


APPENDIX. 

Metric  System  of  Weights  and  Measures 437 

Gallons  Equivalent  to  Liters 438 

Pounds  per  Cubic  and  Square  Equivalent  to  Kilograms  per  Cubic  and  Square    .    .    .  438 

Cubic  Meters  and  Centimeters  Equivalent  to  Cubic  Feet  and  Cubic  Inches 438 

Kilograms  per  Meter  and  Square  Meter  Equivalent  to  Pounds  per  Foot  and  Square  Foot   .  439 

Foot-Horse  Power  Equivalent  to  Metric  Horse-Power 439 

Foot-Pound  Equivalent  to  Kilogram  Meters 439 

Gross  Tons  per  Square  Foot  Equivalent  to  Metric  Tons  per  Square  Meter 439 

Specific  Gravities  and  Weights  of  Various  Substances 440 

Inches  and  Feet  Equivalent  to  Millimeters  and  Meters 441 

Square  Inches  and  Square  Feet  Equivalent  to  Square  Centimeters  and  Square  Meters  441 

Pounds  and  Net  Tons  Equivalent  to  Kilograms  and  Metric  Tons 441 

Units  of  Weights  and  Measures  (Volume) 442 

Units  of  Weights  and  Measures  (Length  and  Surface)      443 

Units  of  Weights  and  Measures  (Weight) 444 

Units  of  Weights  and  Measures  (Miscellaneous) 445,  446 

Decimals  of  a  Foot,  Equivalent  to  Inches  and  Fractions  of  an  Inch 447 

Decimal  Inches  and  Millimeters  Equivalent  to  Fractions  of  an  Inch 447 


STEAM-ELECTRIC  POWER  PLANTS. 


CHAPTER   I. 
GENERAL  REMARKS,  EFFICIENCY  AND  COST  OF  PLANTS. 

Practical  Problems.  —  The  problems  involved  in  the  design  of  steam-electric 
power  plants  must  necessarily  be  treated  in  conjunction  with  cost  of  construction, 
installation,  operation  and  maintenance,  it  being  the  ultimate  aim  of  engineer  and 
capitalist  to  produce  electricity  at  a  minimum  of  expense.  To  accomplish  this  end, 
much  experience  is  necessary.  It  is  not  the  province  of  the  engineer  as  a  designer 
of  power  plants,  to  design  any  particular  machine  or  device,  but  to  provide,  by  selec- 
tion horn  different  makes,  an  assemblage  of  machines  and  devices,  each  designed 
to  perform  its  particular  function  in  the  most  economical  manner,  and  to  combine 
them  so  as  to  create  one  complete  unit  for  the  purpose  of  generating  electricity  from 
coal  on  a  commercially  satisfactory  basis.  Upon  his  skill  in  selecting  machines  and 
devices  will  depend  the  satisfactory  and  economical  operation  of  the  plant.  He  must 
exercise  great  care  and  foresight  in  arranging  these  devices  since,  for  example,  a  prime 
mover,  purchased  to  operate  at  a  certain  rate  of  steam  consumption  per  indicated 
horse  power,  and  not  properly  connected  to  the  boilers  and  auxiliary  devices,  may 
have  its  steam  consumption  materially  increased. 

In  laying  out  a  plant,  selecting  the  various  machines  and  appliances,  arranging 
and  connecting  them  in  their  proper  relation,  originality  should  be  exercised.  No 
designer  should  unreservedly  copy  the  scheme  of  an  existing  plant,  since  what  would 
be  economical  in  one  plant  might  be  the  reverse  in  another. 

Any  attempt  to  standardize  the  design  of  power  plants  would  operate  to  the  dis- 
advantage of  designers,  inasmuch  as  it  would  entirely  eliminate  small  competitors  and 
would  throw  all  the  business  to  a  few  large  concerns,  who  would  in  time  become  too 
independent,  and  would  stay  progress,  since  these  manufacturers  would  have  no  incen- 
tive to  improve  their  machines,  and  improvements  would  be  checked  if  the  designer 
had  to  accept  their  goods  as  offered. 

The  various  branches  of  the  work,  excavation,  foundations  and  structural;  archi- 
tectural, mechanical  and  electrical,  are  so  closely  allied  that  it  is  absolutely  necessary 
that  the  entire  design  of  a  plant  should  be  placed  under  one  engineer  who  should  be  in 
charge  of  the  designers  of  the  various  branches.  If  this  or  similar  method  be  not  fol- 
lowed, confusion  will  result,  delaying  the  work  and  incurring  additional  expense;  com- 
plete co-operation  will  not  exist  and  the  various  designers  will  conflict  with  one  another; 
for  instance,  the  same  article  or  work  may  appear  in  two  or  more  drawings  or  specifica- 
tions, or  may  be  entirely  omitted,  one  designer  considering  it  as  part  of  another's  work. 


STEAM-ELECTRIC    POWER    PLANTS. 


Before  submitting  plans  and  specifications  to  the  contractors  for  bids,  they  should 
be  complete  in  every  detail,  in  fact,  they  should  be  working  drawings.  If  this  plan  be 
followed  the  extras  will  be  minimized.  Extras  are  usually  overcharged,  since  it  is  by 
this  means  that  some  contractors  look  for  their  profits.  For  instance,  the  contract  for 
the  structural  steel  may  be  let  from  a  preliminary  plan,  on  a  per  pound  basis  of  say  from 
three  to  four  cents;  when,  however,  the  plans  are  worked  out  in  detail,  it  may  be  found 
that  there  are  a  number  of  staircases,  openings,  gratings,  ladders  and  railings  required 
but  not  shown  on  the  preliminary  plans;  the  contractor,  on  the  plea  that  more  workman- 
ship is  required  with  this  kind  of  work,  may  raise  his  price  to  seven  or  eight  cents  per 
pound,  or  even  more.  A  considerable  sum  of  money  will  be  saved  by  embodying  all 
this  work  in  one  contract.  For  certain  features,  such  as  chimneys,  boilers,  and  the  main 
prime  movers,  etc.,  preliminary  bids  may  be  asked  for  from  rough  plans  to  ascer- 
tain the  approximate  cost  of  the  plant.  This  may  be  necessary,  when  the  designer  is 
limited  to  a  certain  fixed  sum,  and  especially  if  the  experience  of  the  designer  is  limited. 

The  specifications  should  be  drawn  so  as  to  amplify  and  explain  the  plans,  and  each 
contractor's  specification  should  be  so  drawn  that  there  will  be  no  confusion,  one  con- 
tractor starting  where  the  previous  contractor  stops,  so  that  the  work  will  not  overlap, 
or  gaps  be  left. 

Efficiency. — The  efficiency  of  a  steam-electric  plant  is  low,  ranging  from  8  per  cent 
to  1 6  per  cent  of  the  heat  value  of  the  coal.  Sixteen  per  cent  is  extremely  economical 

TABLE  I. —APPROXIMATE    LOSSES    IN    A    WELL-CONDUCTED    FIRST-CLASS   POWER 

PLANT,  PER   POUND    OF   COAL. 


Subject. 

Losses  in  B.  T.  U.  and  Percentages 
per  Pound  of  Coal. 

14,000  B.  T.  U. 

100  %. 

Ashes                             .        

2IO 
560 
I4O 
I.QOO 
210 
210 
I4O 
8,540 
28 
QIO 

i-5 
4- 
i  .0 
14. 
i-S 
i-5 

I  .0 

61. 

0.  2 
6-5 

Radiation  and  leakage  of  boiler  

Radiation  and  leakage  of  flue  .    .        

Gases  through  chimney.            

Blow-off  and  leakage                      

Radiation  and  leakage  of  piping      

Friction  and  leakage  of  engine     

Rejected  to  condensers  

Electrical  loss  

Required  for  all  auxiliaries   

12,908 

92.2 

Returned  by  Feed  Water  Heater  5  per  cent  or  700  B.T.U. 

Delivered  to  the  bus-bars  105    —  92.2  =  12.8  per  cent  or  1.792  B.T.U. 

and  can  only  be  secured  by  the  best  designed  and  equipped  plant  and  by  scientific  opera- 
tion. The  average  plant  of  recent  construction  operates  with  an  efficiency  of  from 
10  per  cent  to  14  per  cent. 

The  accompanying  table,  Fig.  i,  shows  the  approximate  loss  per  pound  of  coal  in 
a  well  conducted,  first-class  power  plant.  It  will  be  noticed  that  the  coal  is  assumed  to 
have  a  heating  value  of  14,000  B.T.U.  of  which  the  equivalent  of  12.8  per  cent  or 
1792  B.T.U.  are  delivered  to  the  bus-bars. 


GENERAL  REMARKS.  3 

Since  the  efficiency  of  a  steam-electric  plant  is  so  low,  every  increase  in  percentage 
of  economy,  be  it  ever  so  small  a  fraction,  will  materially  improve  the  general  results. 
The  loss  of  heat  accompanying  the  escaping  flue  gases  may  be  minimized  by  employing  a 
properly  designed  boiler,  properly  set  and  connected  to  a  well  designed  chimney.  The  use 
of  mechanical  draught  may  still  further  reduce  this  loss,  while  at  the  same  time  an  intel- 
ligent and  well  conducted  fire-room  force  is  also  conducive  to  economy;  for  instance,  the 
installation  of  carbon  dioxide  (C  O2)  recorders,  from  which  the  fireman  can  read  whether 
he  is  having  complete  combustion  of  the  fuel  or  not,  will  facilitate  intelligent  operation. 

Another  point  which  the  designer  should  consider  is  the  method  of  heating  the  feed 
water.  This  may  be  done  either  by  the  exhaust  steam  of  the  auxiliary  machinery, 
with  economizers,  or  a  combination  of  both.  The  higher  the  temperature  of  the  feed 
water  the  greater  the  gain. 

An  important  factor  in  the  economy  of  power  plants  is  the  superheater.  By  its 
installation  the  steam  consumption  is  lowered,  because  the  condensation  in  the  mains 
and  engine  cylinders  is  considerably  reduced.  Practice  has  proved  that  with  the  use 
of  modern  engines  this  reduction  amounts  to  i  per  cent  of  the  steam  consumption  for 
each  5  degrees  C.  (9  degrees  Fahr.)  of  superheat.  This  applies,  of  course,  up  to  a 
certain  degree  of  temperature,  above  which  there  is  no  further  increase  in  economy. 
The  prime  movers  selected  should  be  capable  of  withstanding  a  high  degree  of  tem- 
perature without  material  depreciation.  By  high  degree  of  temperature  in  American 
practice  is  meant  a  maximum  temperature  of  500  to  600  degrees  Fahr.,  or  in  Continental 
practice,  600  to  700  degrees  Fahr.,  and  even  higher. 

In  selecting  the  prime  mover,  either  reciprocating  engine  or  steam  turbine,  one 
with  the  lowest  steam  consumption,  provided  the  first  cost  is  not  too  excessive,  should 
be  used.  The  guarantee  test  should  be  made  on  the  power  plant  under  actual  work- 
ing conditions  and  under  no  circumstances  should  it  be  made  in  the  manufacturer's 
shops,  since  the  conditions  may  be  entirely  different,  the  manufacturer's  testing  plant 
being  perhaps  fitted  for  ideal  conditions. 

A  "modern"  prime  mover  should  be  able  to  operate  with  a  steam  consumption 
under  normal  rated  load  of  from  n  to  10  pounds  per  I.H.P.  hour,  or  lower.  Manu- 
facturers on  the  continent  of  Europe  sell  prime  movers  (reciprocating  engines  and 
turbines)  with  a  guaranteed  steam  consumption  of  from  10  to  9  pounds  and  lower. 
These  figures  are,  of  course,  based  on  the  use  of  high  temperature  steam  and  a  vacuum 
of  approximately  27  inches. 

In  the  selection  of  auxiliary  machinery,  such  as  condensers  and  pumps,  the  type 
of  prime  movers  should  be  considered.  With  the  use  of  turbines,  surface  condensers 
are  usually  of  greater  efficiency;  while  with  reciprocating  engines,  jet  condensers  may 
be  successfully  employed.  It  is  a  recognized  fact  that  the  greater  the  number  of 
expansions  in  a  turbine,  the  higher  will  be  the  efficiency,  which  cannot  strictly  be 
said  to  apply  to  the  reciprocating  engine,  because  of  the  heavy  cylinder  condensation, 
due  to  the  alternate  heating  and  cooling  of  the  walls  of  the  cylinders;  while  with  many 
makes  of  turbines  a  uniform  temperature  is  maintained  throughout,  and  with  each 
inch  increase  in  vacuum  over  26  inches,  a  saving  of  from  3  per  cent  to  5  per  cent  is 


STEAM-ELECTRIC    POWER    PLANTS. 


obtained.  Of  course,  larger  apparatus  is  required  to  obtain  high  vacuum,  and  it  is, 
therefore,  especially  essential  to  select  pumps  of  high  efficiency. 

There  are,  of  course,  many  other  items  to  be  taken  into  consideration  to  secure  har- 
monious operation  of  the  various  machines,  the  ultimate  aim  being  to  turn  out  a  kilo- 
watt for  the  least  amount  of  money.  The  economical  operation  of  a  plant  is  due  to  a 
great  extent,  first  to  the  designer,  who  selects  high  efficiency  machinery  and  combines 
the  same  properly,  and  secondly  to  the  operators. 

The  operation  of  a  steam-electric  power  plant  may  be  divided  into  two  main  stages: 
the  first,  the  utilization  of  the  latent  heat  in  the  coal  by  the  conversion  of  water  into 
steam  ;  the  second,  the  conversion  of  the  energy  of  the  steam  into  electrical  energy. 

The  heat  latent  in  the  coal  is  expressed,  in  English  speaking  countries,  in  British 
Thermal  units  (B.T.U.).  One  B.T.U.  is  the  amount  of  heat  required  to  raise  one 
pound  of  water  (at  39.  i  degrees  Fahr.)  one  degree  Fahr.  In  countries  where  the  metric 
system  is  used  the  unit  of  heat  is  called  the  Calorie  (C.),  and  is  the  amount  of  heat 
required  to  raise  one  kilogram,  which  equals  one  liter  of  water  (at  4  degrees  C.),  one 
degree  C.  There  is  also  the  small  calorie  (c)  or  gram  calorie,  which  is  the  one-thou- 
sandth part  of  a  calorie  and  is  used  exclusively  for  scientific  work. 

In  order  to  convert  B.T.U.  to  C.,  divide  the  number  of  B.T.U.  by  3.968,  or  multi- 
ply by  0.252.  For  the  purpose  of  transforming  heat  units  into  mechanical  units  the 
following  Table  II  gives  the  equivalents: 

TABLE  II.— EQUIVALENTS  OF  HEAT  AND  MECHANICAL  UNITS  IN   ENGLISH  AND 

METRIC   SYSTEMS. 


B.T.U. 

Foot  Pound 

Calorie. 

Meter 
Kilogram. 

British  Thermal  Units         

I 

778 

0.  2521 

107.6 

0.001285 

I 

0.000324 

0.  1382 

3.068 

3081 

I 

427 

Meter  Kilogram                             

0.0093 

7.  23 

0.00234 

I 

The  size  of  the  plant  is  usually  expressed  in  horse  power  (H.P.)  or  kilowatt  (K.W.), 
the  latter  being  more  generally  used  since  the  introduction  of  the  steam  turbine.  One 
H.P.  equals  33,000  foot  pounds,  or  75  meter  kilograms,  or  .746  K.W.;  the  H.P.  of 
the  prime  movers  should  be  50  per  cent  in  excess  of  the  output  of  the  generator  in 
K.W.  —  for  instance,  a  1,000  K.W.  generator  will  require  a  1,500  H.P.  prime  mover. 
This  percentage  of  increase  includes  the  friction  losses  since,  actually,  one  K.W.  equals 
1.34  H.P.  If  the  output  of  a  combined  unit  is  given  in  H.P.,  deduct  33^  per  cent  to 
convert  to  K.W. 

Cost. —  The  cost  of  a  power  plant  depends  upon  its  character  and  equipment,  and,  to 
a  very  great  extent,  upon  the  capability  of  the  designer.  The  greatest  "errors"  made 
by  designers  are  in  the  choice  of  machinery  for  particular  conditions.  This  is  due  to 
lack  of  experience  and  unfamiliarity  with  up-to-date  machinery.  Many  such  "errors" 
are  discovered  after  the  machinery  has  been  bought,  and  during  the  process  of  design- 
ing, while  many  other  errors  are  discovered  during  the  course  of  construction,  and 
especially  afterwards  in  the  operation.  In  fact,  some  plants  have  been  designed  with 
too  small  a  boiler  capacity  on  account  of  which  blowers  have  to  be  added,  but,  owing 


GENERAL    REMARKS.  5 

to  the  design,  it  is  impossible  properly  to  locate  these  blowers.  Other  cases  have 
occurred  with  the  structural  steel  in  the  basement  X  braced,  thus  preventing  the  laying 
of  air  ducts.  To  overcome  this  difficulty,  the  more  expensive  induced  draught  system 
is  installed,  or,  if  possible,  the  height  of  the  chimney  is  increased.  On  the  other  hand, 
plants  have  been  installed  with  the  boiler  capacity  some  30  to  40  per  cent  too 
large.  This,  of  course,  would  not  affect  the  operation,  but,  besides  the  increased  first 
cost,  it  entails  a  decided  increase  of  the  interest  on  the  investment,  and  additional 
depreciation  and  maintenance.  Other  plants  have  been  designed  with  the  entire 
piping  system  more  than  50  per  cent  too  large.  In  addition  to  the  piping  being 
designed  too  large,  some  of  the  pipes  are  entirely  unnecessary.  Another  plant  has  been 
designed,  so  that  practically  the  entire  condenser  equipment  of  eight  50x30  K.W.  units 
had  to  be  replaced  by  another  system. 

The  enormous  expense  of  these  changes  may  be  easily  appreciated.  It  will,  therefore, 
be  seen  that  it  is  a  paying  investment  to  engage,  or  consult,  men  of  broad  experience. 

The  ratio  of  operating  and  maintenance  costs  of  reciprocating  engine  and  steam 
turbine  plants  may  be  10  to  8  or  8|.  This  is  due  to  lower  steam  and  coal  consumption 
in  the  latter  case,  since  the  water  of  condensation  may  be  returned  directly  to  the  boiler. 
The  labor  for  attendance  on  a  turbine  plant  is  practically  negligible.  In  further  con- 
sidering the  cost  of  a  power  plant,  the  advisability  of  installing  a  condenser  must  be 
carefully  considered.  This,  however,  does  not  necessarily  mean  that  the  omitting  of 
the  condenser  apparatus  will  result  in  a  lower  first  cost,  since,  on  account  of  the  higher 
steam  consumption  of  a  non-condensing  engine,  which  may  reach  30  to  40  per  cent  and 
even  higher,  larger  prime  movers,  boilers,  and  consequently  auxiliary  machinery  and 
building  must  be  provided. 

The  accompanying  Tables,  III  and  IV,  give  average  prices  of  plants  equipped  with 
turbines  and  reciprocating  engines.  It  is  assumed  that  units  are  installed  of  3,000  to 
5.000  K.W.  capacity  or  above.  It  will  also  be  noticed  that  each  table  consists  of  two 
columns,  the  first  giving  prices  arrived  at  by  skilled  engineering  and  favorable 
conditions,  the  second  giving  prices  of  plants  which  were  high,  due  to  inferior  design 
and  selection  of  equipment.  These  latter  figures  do  not,  however,  represent  the 
highest  cost  of  plants  actually  installed,  for  it  is  understood  that  the  L  Street  Station 
in  Boston  cost  about  $125.00  per  K.W.,  while  the  cost  of  the  59th  Street  Station,  New 
York  City,  amounts  to  nearly  $150.00  per  K.W.  This  large  variation  in  cost  is  only 
partly  due  to  high  costs  of  buildings,  which  are  recognized  as  the  finest  buildings  in 
the  country  for  the  purpose.  The  superstructure  of  the  latter  station  amounts  to 
$32.00  per  K.W.,  while  the  condenser  equipment  of  this  station  and  the  boiler 
equipment  of  the  former  power  station  are  excessively  high. 

Reverting  to  these  tables  it  will  be  noted,  by  comparison,  that  the  turbine  plants 
are  somewhat  lower  in  cost  than  the  engine  plants.  This  is  owing  to  the  smaller  founda- 
tions required,  and,  possibly,  also  to  the  fact  that  a  smaller  building  serves.  Further- 
more, the  turbo-generator  costs  less  than  combined  engines  and  generator,  although 
the  prices  of  the  former  are  generally  governed  by  the  prices  of  the  latter. 

Again,  the  condenser  equipment  is  more  expensive  for  the  turbine  plants,  for  the 


STEAM-ELECTRIC    POWER    PLANTS. 


surface  condensers  usually  installed  cost  more,  and,  owing  to  the  higher  vacuum  main- 
tained, larger  pumps  are  required. 

These  costs  apply  to  plants  of  medium  and  large  capacity,  the  costs  of  small  size 
plants  being  treated  in  Chapter  VIII.  It  must  be  borne  in  mind  that  the  cost  per 
K.W.  increases  very  rapidly  as  the  capacity  of  plant  is  decreased. 

TABLE  III.  —  COST    OF    TURBINE    PLANTS. 


Excavations  and  Foundations  

$2.00 

$2.  SO 

Building                        

IO.OO 

I  S  OO 

Tunnels                         .        

I.7S 

A.  OO 

Flues  and  Stacks                         

2  SO 

SCO 

Boilers  and  Stokers            

8.  so 

12  OO 

Superheaters    

2.OO 

2.  SO 

Economizers                             

2  OO 

2  2S 

Coal  and  Ash  Handling  System  

I.  SO 

1  OO 

Blowers  and  Ducts     

I.OO 

I.  SO 

Pumps  and  Tanks      

I.OO 

I   2S 

Piping,  Complete    

2.2S 

4..  SO 

Turbo-Generators  

22.OO 

2S  OO 

Condensers,  Surface  

5  oo 

8  oo 

Exciters     .        .. 

.78 

I  OO 

Cranes  

.2? 

.so 

Switchboard     

2.OO 

3.  so 

Labor,  etc  

I.OO 

2  OO 

$65.50 

$92.00 

TABLE  IV.  —  COST    OF    ENGINE    PLANTS. 


Excavation  and  Foundation  

$3.00 

$S.oo 

Building   .            

IO.OO 

20.00 

Tunnels    .    .    .•    

I.  SO 

2.7S 

Flues  and  Stacks    .            

2.^0 

7.  SO 

Boilers  and  Stokers    

8.  so 

I2.OO 

Superheaters    

i.7S 

2.2S 

Economizers    

2.OO 

2.2S 

Coal  and  Ash  Handling  System  

I.  SO 

•?.oo 

Blowers  and  Ducts     

I.OO 

I.  SO 

Pumps  and  Tanks      

I.OO 

I.2S 

Piping,  Complete    .        ...        

2.  SO 

S.oo 

Engines     

18.00 

22.00 

Condensers,  Jet  .            ...        .        

•?.oo 

S.oo 

Exciters    

•  7S 

I.OO 

Generators   

IO.OO 

I2.OO 

Cranes  .                

•  2S 

•  SO 

Switchboard     

2.OO 

"?-So 

Labor,  etc  

I.OO 

2.OO 

$70.25 

$104.50 

During  the  discussion  of  a  paper  on  power  station  design,  by  Messrs.  Merz  and 
McClellan  before  the  Institute  of  Electrical  Engineers,  London,  Mr.  H.  L.  Leach 
presented  the  accompanying  table,  showing  the  relative  cost  per  unit  generated  in 
London  and  in  provincial  plants.  It  is  hardly  necessary  to  make  any  further  comment 
on  it,  since  it  speaks  for  itself. 


GENERAL    REMARKS. 


u 


Cost  per 
Kilowatt. 

S?  ro 

M      CO    CO    t^»    CO    CD    Ol 
10    CO    •*    CO    CO    rf    CO 

I         VO         M 

|        NO      NO 

1 

11 

^fe 

S  o 

8| 

£" 

OO     CO  OO      1-1      w      M      M 
ON    ON    oo    CO    O      CO    M 

CO     6      t~~-    "*•     •<*•     04      IO 

M       Ol       M       M       M       M       04 

NO      t^    ON 
Ol      O    O 
04       O4       r-. 

M       M       M 

0 

01 

$ 

11 

10 
Ol 
T3     10 

t^.   NO       Tj-      ro     H     00       01 
rt-   NO      01      10     ON     ON  NO 
IO    ON    *^    ^1"     CO     ON    Ol 

10    10 

I      oi     o 

1     *?     1 

1 

Hu 

04       04 

H 

O 

U 

ufai 

Sue8 

SQ-i  S 

IO 

r^. 

T3     01 

t^  00     rf  00    00     ro    oo 

OO       ON     O       O       Tf     CO     M 

w     rt-    t~-    ON   f^    10  'O 

ro     ON 

1       ro    r^ 
|     ^0     0 

1 

o 

^ 

CTJ   d  0. 

M  c'G  o 

t3            M 

M                                                       M 

M        M 

III 

££u 

O 

IO 

73     « 

O     OO       O       10     CO     10     ON 

VO       MO         IN         Tt       Tj-     NO         OO 

r^    T)-     O     10  NO      •*  MO 

00       04     NO 
XO    ON    04 
00      ON    O 

M 

O 
* 

rt- 

g 

I 

NO 

•d  o° 

10   t  —    O     "^"    01     to   t^ 

O       w      **•     ON     IO     O       " 

M        M        M        M        OJ        M        M 

t^    •<*•   10 

ON    O     00 
Ol     ro    M 

00 

04 
O 

« 

JATED. 

U 
bo 

•* 

•«  ? 

O<       M      l>-     O       Ol      1^    IO 

OO     r^  00     r^    oj     M     ro 

M      NO      NO 

O 

IO 

0 

H 
U 

£ 

b 

Z 
P 

^   o 

•S  s 

^cH 

0 

•d  S 

ro    to    O     10    ro    fd    ^ 
0)     •*  NO     ro    •*    01     10 
O     O     O      O     O     O     O 

^0      0     <* 
Ol      Th  NO 
000 

NO 

* 

0 

H 

Pi 

_-T3 
O   rt 

i 

0 

•d  IT 

O     Tt    ro  >O    NO      O     ro 
>O    ro     O      •*     04      H      OO 
M     M    NO     oq     01     Ol     ro 

•*      01        H 

1^.    t^    o 

ro    •*•  NO 

o 

ro 

i 

NO     ON  ^O     *)•    ?>     ro    Tf 
00    OO    ^O     to    M     ro    M 
!>.    IH      ON    ON  ^O     10    rO 

04     NO       M 

10  oo    r-» 

CO     *^     ON 

r^ 

00 
0 

11 

^  G 

IO     IO     M     NO      t^     w       04 

^j-     CN1       04       ON     ON     ro   NO 

tf)      t-t         (-H         M         M         ON      f>* 

ON  >O    OO 
M     t^-    ro 
•<t  NO     ro 

M 

00 

4>. 

o 

r-    O    00     O     ro    to   10 

M                    MM                    Ol 

+_4—                  H—  -J— 

t<»  «C  rC 

M         I-H 

4—  4— 

CO 

* 

O 

. 

•  u 

« 

g 

c 

^2 

8s 

V    '•£ 
C     cd 

C.      U      >         <|          0          V          « 

c« 

o    d'S 

ou^ 

c 

•s 

o 

15 
w5 

^w 

G 
o 

S 
« 
e 

9 

S 

H   g,  

M       - 

^^    «^&       1 

R     s     O     *J     £              O 

s  ^  ^  |  So  «  e- 

I!  ^  .5?^  ^8  ^  > 

OJ     u     t.    T3    —  '      1)    .M 

£  pq  «  w  O  J  (-1 

g  §  * 

ll* 

o    o     . 

h5  J  8 

•s  ^  1 
^  ^^ 
u  u  ti 

J2 

^ 
O 

an 

a 
£. 
u 

•S2 
h3 

^s 

CO    ro    ro    ro 
1        1        1        1 
N       N       Ol       04       O4       04       Ol 

O     O     O     O     O     O     O 

ON     ON     ON     ON     ON     ON     ON 

ro    O4      04 

ON    ON    ON 

04 

O 

ON 

^^ 

oo  3. 


STEAM-ELECTRIC   POWER  PLANTS. 


Portsmouth  (Ohio)  Light  and  Power  Plant  (The  Engineer}. 


CHAPTER   II. 
LOCATION. 

Introductory.  —  Modern  systems  of  electrical  distribution  permit  of  much  greater 
liberty  in  the  selection  of  a  site  for  the  main  generating  station  than  was  possible  in 
the  early  days  of  the  art.  Formerly  it  was  almost  a  necessity  that  the  station  should 
be  situated  at  the  central  portion  of  the  area  served,  and  in  such  locations  land  was 
high  priced  and  difficult  to  secure.  As  a  result  many  central  stations  were  built  on 
abnormal  designs,  in  the  endeavor  to  crowd  sufficient  generating  capacity  into  the 
limited  area  available.  In  such  plants  it  was  impossible  to  secure  the  best  results,  and 
the  ultimate  fate  of  many  has  been  to  become  sub-stations,  at  which  high-tension  cur- 
rent is  transformed  to  a  voltage  suited  for  the  local  service.  By  the  use  of  high-tension 
systems  of  distribution,  the  radius  within  \vhich  it  is  possible  to  locate  the  main  gen- 
erating station  has  been  enormously  extended,  and  improved  facilities  thereby  obtain- 
able for  the  handling  of  coal  and  ashes,  etc.  This  reduces  the  operating  expenses  and 
fixed  charges,  to  an  extent  that  more  than  counterbalances  the  transmission  and 
transformer  losses. 

In  short,  the  most  important  points  which  have  to  be  considered  in  the  location  of 
the  main  generating  station,  are  as  follows,  viz. : 

I.  System  of  distribution  to  be  used. 

II.  Facility  with  which, coal  may  be  received  and  ashes  disposed  of. 

III.  Water  supply  available  for  boiler  feed  and  condensers. 

IV.  Space  available  for  future  expansion  and  coal  storage. 
V.  The  cost  of  the  land. 

VI.  The  character  of  the  ground  with  reference  to  its  influence  upon  the  expense 
required  in  putting  in  suitable  foundations. 

VII.  Convenience  and  accessibility  of  the  site  for  the  operating  force,  the  availa- 
ble supply  of  labor,  etc. 

Current  Distribution.  —  The  system  of  distribution  adopted  will  determine  whether 
the  site  must  be  in  the  more  expensive  business  district,  as  in  the  case  with  low-tension 
lines,  or  in  a  neighborhood  where  land  is  less  costly;  in  the  manufacturing  suburbs  or 
at  a  considerable  distance,  as  is  permissible  when  high-tension  transmission  lines  are 
to  be  used,  though  in  this  latter  case  it  may  not  always  be  possible  to  use  high-tension 
distributing  systems  on  account  of  local  laws  and  regulations. 

Coal  Supply.  — •  It  is  impossible  to  secure  permission  to  erect  a  power  plant  in  certain 
sections  of  some  cities,  owing  to  the  smoke  nuisance,  while  in  other  cities  permission  may 

9 


10  STEAM-ELECTRIC    POWER    PLANTS. 

be  granted,  provided  the  buildings  conform  in  appearance,  and  will  be  maintained  at 
all  times  in  harmony  with  the  surroundings;  that  suitable  means  will  be  provided  for 
the  prevention  of  smoke  and  for  the  disposal  of  waste  steam,  etc.,  and  that  the  hours 
during  which  fuel  may  be  delivered  and  ashes  removed  will  be  restricted  to  such  as 
will  cause  the  least  inconvenience  to  the  neighborhood.  Plants  in  such  localities  are 
hampered  in  many  ways  and  are  liable  to  numerous  suits  for  damages,  with  their 
resulting  expense.  As  an  example  of  this  a  decision  was  handed  down  in  the  appellate 
division  of  the  Supreme  Court  of  the  State  of  New  York,  whereby  the  26th  Street 
Station  of  the  Edison  Electric  Illuminating  Company  of  New  York  City,  which  was 
built  in  1888,  was  declared  a  nuisance,  and  damages  were  awarded  to  an  adjacent 
property  holder. 

In  almost  all  cases  a  good  location  for  a  generating  station  is  near  a  gas  works,  or 
in  a  factory  neighborhood,  such  plants  being  usually  located  close  to  a  railroad  or 
waterway,  by  means  of  which  coal  and  ashes  can  be  conveniently  handled.  Such 
conveniences  are  of  great  service  during  construction  for  the  delivery  of  building 
materials,  machinery,  e'c.  In  such  localities  it  is  usually  possible  to  arrange  for  a  side 
track  to  be  built  to  the  property,  whence  tracks  can  be  laid  into  the  building  so  that 
boilers  and  heavy  machinery  a.n  be  readily  handled.  When  it  is  possible  to  do  so,  a 
site  should  be  selected  where  both  land  and  water  transportation  facilities  are  present, 
to  insure  continuity  of  fuel  supply.  To  guard  against  interruptions,  provision  should 
be  made,  near  the  plant  if  possible,  for  the  storage  of  a  sufficient  quantity  of  coal  to 
carry  over  the  probable  length  of  time  of  such  interruptions,  during  several  weeks  or 
for  longer  periods  if  it  be  possible. 

The  New  York  Edison  Company  experienced  considerable  trouble  in  1902  when 
there  was  a  strike  in  the  anthracite  coal  regions,  of  several  months  duration,  and  they 
have  since  erected  a  large  coal  storage  plant  as  a  reserve  supply  for  their  various  gen- 
erating stations  located  in  New  York  City.  Owing  to  the  fact  that  it  was  impossible 
to  secure  sufficient  space  for  this  purpose,  at  a  reasonable  cost,  at  the  various  stations, 
this  plant  has  been  located  at  Shadyside,  N.J.,  on  the  Hudson  River,  where  the  coal 
is  usually  delivered  in  cars,  and  whence  it  is  transported  in  barges  either  directly  to  the 
generating  station  or  to  a  pier  whence  it  is  carted  to  the  power  plant.  The  complete 
plant  provides  a  storage  capacity  of  150,000  tons,  two-thirds  for  anthracite  coal,  and 
the  remainder  for  bituminous  coal. 

In  the  case  of  the  twin  municipal  plant  of  Vienna,  Austria,  each  portion  has  been 
provided  with  coal  storage  for  six  weeks,  while  in  many  other  European  plants  the  coal 
capacity  is  such  as  will  carry  them  over  the  frequent  short  strikes,  lasting  from  two 
to  eight  weeks. 

It  might  be  considered  a  good  plan  to  locate  the  generating  station  adjacent  to  the 
coal  mine,  whereby  the  cost  of  fuel  would  be  greatly  reduced,  and  to  distribute  the 
current  to  cities  and  factories  by  high-tension  transmission  lines.  This  project,  however, 
is  by  no  means  a  new  one,  and  has  been  discussed  several  times  in  the  technical  press. 
It  is  perfectly  feasible  and  may  yet  be  done.  Some  of  the  more  prominent  firms  in 
Germany  recently  proposed  to  erect  a  large  central  station,  in  the  Rhenish-Westphalian 


LOCATION.  1 1 

coal  region,  which  is  one  of  the  largest  manufacturing  districts  of  the  Empire.     The 
plan  has  been  partly  carried  out  with  success. 

In  the  case  of  the  Mexican  Light  and  Power  Company,  supplying  the  City 
of  Mexico,  we  have  an  example  of  the  transmission  of  electricity  over  a  distance  of  1 73 
miles  (the  initial  voltage  being  67.500).  There  are  instances  in  which  a  tension  of  80,000 
volts  is  used,  while  lines  operated  with  100,000  and  more  are  now  under  consideration. 
These  plants,  however,  are  operated  by  water  power  and  the  sites  of  the  stations  were 
determined  by  this  factor.  With  steam-operated  plants  the  question  is  simply  whether 
it  is  cheaper  to  transport  the  coal  to  a  station  close  to  the  center  of  distribution,  or  to 
transmit  current  over  this  distance,  but  at  the  same  time  the  liability  to  interruptions 
must  be  taken  into  account.  Unreliable  service  will  result  in  serious  competition 
springing  up,  with  consequent  loss  oFTnisiness. 

Water  Supply.  —  The  available  water  supply  is  an  important  question,  particularly 
for  condensation,  and  for  this  reason  many  plants  using  reciprocating  engines  were 
located  at  the  water's  edge.  In  such  plants  the  vacuum  is  rarely  higher  than  25  to  26 
inches,  while  with  the  advent  of  the  steam  turbine  much  higher  vacua  became  desirable 
owing  to  the  increased  economy  of  the  turbine  under  such  conditions,  and  thereby  the 
quantity  of  circulating  wrater  required  has  been  doubled  and  in  some  cases  nearly 
trebled  as  compared  with  the  requirements  of  a  reciprocating  plant. 

From  the  foregoing  it  will  be  seen  that  the  water  question  is  vital.  Where  the  plant 
is  located  adjacent  to  tide  water  this  question  is  complicated  by  the  fact  that  it  is 
undesirable  to  use  salt  water  for  boiler  feed  purposes;  therefore,  it  is  necessary  either 
to  draw  water  from  the  available  local  water  supply,  or,  in  some  cases,  the  water  must 
be  piped  a  considerable  distance,  and  the  amount  of  water  required  will  depend  upon 
whether  surface  or  jet  condensers  are  used ;  in  the  one  case  only  sufficient  water  will  be 
required  to  supply  the  various  losses,  while  in  the  other  the  entire  amount  required 
for  the  boilers  must  be  supplied. 

Space  for  Future  Extension.  —  It  is  desirable  that  the  site  selected  should  have 
room  enough  to  permit  of  the  natural  growth  of  the  plant,  and  be  of  sufficient  addi- 
tional area  to  permit  of  adequate  coal  storage,  suited  to  present  and  future  require- 
ments. In  many  cases  such  considerations  have  been  neglected.  In  some  cases  local 
considerations  are  such  that  it  is  almost  impossible  to  obtain  a  site  with  these  features; 
in  other  cases  the  financial  condition  of  the  company,  in  its  early  days,  has  prevented 
the  acquirement  of  more  land  than  absolutely  necessary  for  immediate  purposes. 
Strong  companies,  too,  have  suffered  from  mismanagement  at  the  start;  in  some  cases 
from  short  sightedness  on  the  part  of  the  directorate,  in  others,  from  a  desire  to  secure 
personal  profit  from  the  company  on  the  part  of  some  official. 

Cost  of  Land.  —  In  many  cases  the  cost  of  the  land  has  been  the  deciding  factor  in 
regard  to  the  location  of  the  plant,  and  all  other  considerations  have  been  ignored,  not- 
withstanding the  fact  that  such  locations  may  add  considerably  to  the  operating  expenses, 


12  STEAM-ELECTRIC    POWER    PLANTS. 

for  the  reason  that  coal  may  have  to  be  hauled  by  wagons  at  considerable  expense  and 
ashes  disposed  of  in  a  similar  manner,  and  as  the  expense  of  this  handling  is  a  continual 
tax,  a  more  conveniently  located  site  will,  in  such  cases,  be  found  necessary  in  a  short 
time.  Cases  have  arisen  in  which  it  was  found  cheaper  to  abandon  the  original 
station,  as  soon  as  it  was  feasible  to  construct  a  new  one,  to  care  for  the  increased  load, 
at  a  point  where  operating  expenses  were  lower. 

Character  of  Soil.  —  The  character  of  the  soil  may  be  an  important  factor  in  the 
selection  of  a  site  for  a  power  house,  the  most  desirable  being,  of  course,  that  which 
entails  the  least  expense  for  foundations.  At  the  same  time  it  must  be  considered, 
that  the  expense  of  the  foundations  has  not  only  to  be  met  at  the  start  but  thereafter 
becomes  a  factor  in  the  fixed  charges.  It  is  possible,  however,  that  a  site  (although 
requiring  expensive  pile  foundations)  may  be  preferable  to  one  whose  foundations  call 
for  a  smaller  initial  outlay,  v.  hen  other  things  are  considered.  It  is  desirable  to  select 
and  secure  options  on  several  sites,  and  if  this  procedure  be  followed,  these  options 
should  permit  borings  to  be  made  from  which  it  will  be  possible  to  determine  the  depth 
and  size  of  the  heaviest  foundations  required.  A  small  expense  incurred  in  this 
manner  will  often  enable  large  sums  to  be  saved.  The  subject  of  foundations  will 
be  further  considered  under  that  heading. 

Local  Labor  Supply.  — The  convenience  and  accessibility  of  the  site  for  the  operat- 
ing force  and  the  labor  supply,  or  the  attractions  which  the  neighborhood  present  that 
would  be  liable  to  make  the  operating  force  contented  in  the  locality,  should  be  consid- 
ered. It  is  comparatively  easy  to  import  a  force  of  men  when  such  cannot  be  secured 
in  the  vicinity,  but  it  takes  more  than  a  steady  position  to  hold  men,  except  in  times 
of  business  depression  when  the  labor  market  is  over  supplied,  and  should  the  plant 
be  inconveniently  located  with  regard  to  residential  districts,  suitable  for  the  various 
grades  of  employees,  it  will  usually  be  found  that  a  certain  amount  of  difficulty  will  be 
met  with  in  holding  some  of  the  most  desirable  men.  On  the  contrary,  in  plants  more 
favorably  located,  it  will  be  found  that  positions  are  sought  after,  and,  in  a  manner, 
such  a  location  becomes  an  invisible  asset  of  no  mean  value. 

GENERAL    LAYOUT    OF    POWER    PLANTS. 

General  Consideration.  — This  heading  may  be  treated  in  the  following  subdivisions: 

I.   BOILER  HOUSE. 
II.   ENGINE  HOUSE. 

III.  SWITCH  ROOM. 

IV.  COAL  STORAGE  PLANT. 
V.  AUXILIARY  BUILDINGS. 

The  practice  of  making  the  boiler  and  engine  houses  separate  buildings  has  long 
since  been  abandoned,  and  it  is  not  to-day  considered  good  practice  to  use  the  long 
steam  pipes  which  are  required  to  span  the  space  between  the  buildings.  These 


GENERAL    LAYOUT. 


long  pipes  caused  a  great  deal  of  condensation,  resulting  in  wet  steam  for  the  engines, 
and  were  dangerous,  owing  to  the  likelihood  of  water  collecting  and  being  carried  over 
to  the  engine  in  such  large  quantities  that  the  relief  valves  on  the  cylinders  could  not 
care  for  it.  Short  pipes  are  also  much  cheaper  to  install  and  to  keep  in  repair.  It  has 
been  the  practice  for  the  last  eight  or  ten  years  to  locate  the  boiler  house  at  the  side  of 
the  engine  house,  as  is  shown  in  Fig.  2.  A  light  division  wall  may  separate  the  two 


FIG.  i. 


rooms,  and  they  may  or  may  not  be  covered  by  a  roof  common  to  both,  depending 
upon  the  size  and  upon  insurance  regulations.  Where  conditions  are  such  that  this 
arrangement  is  not  possible,  owing  to  the  shape  of  the  plot  of  ground,  an  arrangement 
which  may  be  utilized  is  shown  in  Fig.  i.  As  can  be  seen,  with  this  arrangement  the 


FIG.  2. 

steam  pipes  may  be  of  enormous  length,  and  therefore  it  is  not  considered  good  practice, 
and  very  few  plants  have  been  built  along  these  lines.  Where  these  conditions  are 
encountered  it  would  be  preferable,  especially  in  cities  where  land  is  expensive,  to  put 


STEAM-ELECTRIC    POWER    PLANTS. 


the  boiler  room  above  the  engine  room,  as,  for  example,  in  the  power  plant  at  Bristol, 
England,  and  the  Berlin  Underground  and  Elevated  Railroad  plant,  and  the  Duane 
Street  station  of  the  New  York  Edison  Company.  It  may  seem  proper  that  the  boilers 
should  be  on  the  first  floor,  with  the  engines  above  them,  but  in  actual  practice  it  has 
proved  inadvisable,  for  it  is  desirable  that  reciprocating  engines  be  placed  on  the 
ground  floor  on  a  good  solid  foundation.  However,  it  is  possible  with  the  steam  turbine 
to  follow  the  former  arrangement,  for  there  is  no  appreciable  vibration,  and  the  weight 
is  far  less  than  that  of  reciprocating  engine. 

In  Fig.  2  it  will  be  noticed  the  two  rows  of  boilers  are  divided  by  a  common  firing 
aisle,  a  system  adopted  by  the  Chelsea  plant  of  London,  Interborough  Rapid  Transit 
plants  of  New  York  and  the  twin  municipal  plant  of  Vienna,  —  all  plants  of  recent 
construction.  Occasionally  one  will  find  the  boiler  house  provided  with  two  rows  of 
boilers  similar  to  Fig.  2,  but  with  the  boilers  placed  back  to  back,  thus  necessitating 
two  firing  aisles.  A  system  similar  to  this  is  characteristic  of  French  plants,  with  the 
exception  that  the  generating  room  is  between  the  two  rows  of  boilers,  as  indicated  by 
dotted  lines  in  Fig.  3 ;  for  example,  the  Metropolitan  Company's  power  house  in  Paris, 


o 


'• 1  ! — ~! •  r  — -r-1 

:     1 1          > ;     ; 

it     i     1 1 
•     it     i     1 1     i 
• — i — i « — i — i  \ — i_ 


•1  i r— 


i< 

ii 


__j  i — i — i 


I± 


1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

1 

FIG.  3. 

but,  however,  in  this  latter  case,  the  smokestacks  are  located  within  the  boiler  house, 
and  not  as  shown  in  Fig.  3.  This  arrangement  of  the  generating  room,  between  the 
two  boiler  rooms,  is  characteristic  of  the  Frenchman's  artistic  taste  for  architectural 
symmetry.  The  disadvantage  of  this  arrangement  is  that  it  is  not  mechanically  sym- 


GENERAL    LAYOUT.  15 

metrical,  though  the  fact  may  be  considered  that  it  would  be  practically  impossible  for 
a  disaster  to  occur  to  both  boiler  rooms  at  the  same  time. 

There  are  a  number  of  power  plants  in  which  the  boilers  are  arranged  in  two  rows 
in  one  boiler  room,  with  a  firing  aisle  between;  some  of  these  are  double  decked,  notably 
the  Manhattan  power  plant  in  New  York  City,  and  the  Chelsea  plant  of  the  London, 
England,  Underground  Railroad,  while  the  Metropolitan  Traction  Company's  power 
plant  in  New  York  City  has  three  superimposed  tiers  of  boilers.  The  arrangement 
of  the  boiler  house  depends  entirely  upon  the  size  or  capacity  of  the  steam  generating 
unit  selected,  but  when  units  of  over  10,000  square  feet  heating  surface  are  selected, 
as  in  the  Bow  Road  plant,  London,  it  is  hardly  necessary  to  use  a  second  tier. 

With  the  introduction  of  the  steam  turbine  a  great  change  took  place  'in  the  general 
arrangement  of  power  plants;  the  generating  room  with  the  turbine  plant  being  smaller 
than  that  of  the  reciprocating  engine,  owing  to  the  turbo-generating  units  being  much 
more  compact,  and  this  notwithstanding  the  fact  that  with  the  turbine  the  condensing 
apparatus  is  larger  than  with  the  reciprocating  engine.  Recently  the  most  prominent 
plants  have  been  built  on  this  plan,  the  Carville  station  at  Newcastle,  the  Fisk  Street 
station  of  the  Commonwealth  Electric  Company  of  Chicago,  the  latest  Boston  Edison 
station  and  the  Philadelphia  Rapid  Transit  station  being  important  examples,  while 
numerous  others  may  be  mentioned;  viz.,  the  St.  Denis  plant  of  Paris,  France,  now 
being  erected,  which  will,  when  completed,  be  the  largest  turbine  station  in  Europe, 
even  exceeding  the  large  Chelsea  station  in  London.  The  layout  of  this  type  of  plant 
is  shown  in  Figs.  4  and  5.  The  marked  difference  in  the  boiler  arrangement  is  that 


ffVl 

! 

1 

1 
1 

1 

L22 

_, 

1 

1 

o 

1 

(2) 

Cl 
1 
1 
•^~- 

1 

1 
1 

© 

* 

o 

l±3f±l 

1 

1 

1 

i 

1 

1 

(o) 

v^y 

FIG.  4. 

the  rows  of  boilers  do  not  run  parallel  to  the  generating  room,  but  at  right  angles  to  it. 
In  this  way  the  power  plant  is  divided  into  separate  and  distinct  units,  each  row  of 


16 


STEAM-ELECTRIC    POWER    PLANTS. 


boilers  feeding  in  regular  operation  its  own  particular  turbine.  The  arrangement  of 
the  boilers  in  rows  at  right  angles  to  the  engine  room  is  by  no  means  a  new  one.  In 
1898  the  McDonald  Road  Generating  Station,  Edinburgh,  Scotland,  was  designed  on 
these  lines  with  the  engine  rooms  side  by  side,  and  between  two  boiler  rooms  at  right 
angles  with  them.  The  plant  of  the  Central  Electric  Supply  Company  of  London, 
England,  is  of  similar  arrangement;  both  plants  were  designed  by  Dr.  Kennedy.  By 
this  arrangement  the  engine  room  can  be  designed  with  a  minimum  amount  of  floor 
space,  but  at  the  same  time  the  area  of  the  boiler  room  is  increased  over  that  in  which 
two  rows  of  boilers  are  placed  parallel  to  the  engine  room.  The  fancied  economy  of 
the  turbine  in  regard  to  economy  of  floor  space  occupied  has  not  been  realized  in  some 
cases,  owing  to  the  fact  that  the  boilers  have  been  set  at  right  angles  to  the  engine  room ; 
for  instance,  the  Boston,  Mass.,  Edison  Electric  Illuminating  Company's  power  plant 
occupies  2.45  square  feet  of  ground  area  per  K.W.  of  generating  capacity,  while  the 
Interborough  (Subway)  power  plant  in  New  York  City,  where  reciprocating  engines 
are  used,  with  two  parallel  rows  of  boilers  (notwithstanding  the  fact  that  a  great  deal 
of  room  has  been  allowed  around  the  engines),  only  occupies  a  ground  area  of 
2.32  square  feet  per  K.W.  In  both  cases  the  prime  movers  have  a  normal  capacity  of 
5,000  K.W. 

W'here  it  will  require  three  or  more  boilers  to  feed  one  turbo-generating  unit  the 
arrangements  shown  in  Figs.  4  and  5  have  generally  been  found  to  be  advantageous, 
while  for  a  less  number  it  is  advisable  to  follow  the  plan  shown  in  Fig.  2,  but  this  is 
merely  a  matter  of  opinion,  as  prominent  engineers  advocate  both  systems.  In  Fig.  5 


IT 


FIG.  5. 

it  will  be  seen  that  there  are  two  separate  firing  aisles,  and  increasing  the  capacity  of 
the  plant  in  either  direction  increases  their  number,  and  with  the  increase  of  the  number 
of  firing  aisles  the  coal-handling  apparatus  is  likewise  increased.  Where  the  coal  is 


GENERAL    LAYOUT.  I/ 

landed  on  a  truck  at  the  ends  of  the  rows  of  boilers  the  liability  of  interruptions  to  the 
service  occurring  from  mishaps  to  the  conveyor  is  reduced.  In  order  to  avoid  such 
interruptions  in  plants  with  a  single  firing  aisle,  it  is  frequently  found  necessary  to 
install  duplicate  conveyors,  either  one  of  which  is  able  to  handle  the  requirements  of 
the  station.  Conveyor  accidents,  however,  will  not  interfere  with  the  operation  of  the 
plant,  provided  the  coal-storing  capacity  in  the  bunkers  is  sufficient  to  tide  over  the  time 
necessary  for  repairs.  A  good  example  of  how  long  a  plant  may  be  operated,  should 
such  an  accident  occur,  is  the  power  house  of  the  Interborough  Rapid  Transit  Company 
(Subway)  of  New  York  City.  The  firing  aisle  in  this  station  is  693  feet  long  and  the 
storage  capacity  in  the  overhead  bunkers  is  16,000  tons.  It  will  be  seen  that  a  very 
long  longitudinal  conveyor  is  required  to  seive  this  plant;  in  fact,  it  was  found  necessary 
to  cut  it  into  two  sections.  In  a  plant  of  equal  capacity,  with  four  firing  aisles,  each 
could  be  served  by  a  conveyor  about  120  feet  long,  requiring  less  power  than  a  longer 
conveyor.  At  the  same  time,  if  the  bunker  capacity  provided  is  ample  to  run  the  plant 
from  three  to  four  days,  and  if  the  bunkers  are  kept  full,  this  time  will  be  ample  to 
repair  any  conveyor  breakdowns.  In  fact,  one  way  to  insure  reliable  service  is  to  keep 
the  bunkers  full,  but  as  over-long  storage  of  coal  may  result  in  spontaneous  combustion 
in  the  bunkers,  judgment  is  required  in  regard  to  handling  the  supply. 

Complete  Unit  System.  —  In  modern  stations  the  practice  is  to  divide  the  entire 
plant  into  a  series  of  units,  as  has  already  been  mentioned,  each  unit  comprising  a 
prime  mover  and  generator  with  its  condenser  and  attendant  auxiliary  machinery, 
together  with  the  requisite  number  of  boilers.  The  switchboard  is  also  divided  on 
the  same  system,  giving  to  each  generator  a  panel  provided  with  all  the  necessary 
instruments  and  switches.  In  many  cases  it  is  well  to  carry  the  unit  system  further, 
making  it  complete  in  all  particulars,  with  its  own  boiler  feed  pump,  feed-water  heaters, 
economizers  and  chimney.  There  are  many  advantages  to  be  gained  by  arranging 
a  plant  on  this  basis.  The  design  of  all  the  units  being  alike,  new  plans  are  not 
required  when  it  is  desired  to  extend,  and  the  stock  of  spare  parts  is  greatly  reduced. 
Operation  is  more  convenient,  since  men  can  be  shifted  from  unit  to  unit  without 
any  confusion  incident  to  their  not  being  familiar  with  the  piping  system,  etc. ;  trouble 
is  easily  localized  and  the  affected  unit  cut  out,  and  such  plants  are  more  easily  super- 
vised in  operation  and  construction.  During  construction  each  unit  can  be  completed 
and  put  in  operation  by  itself,  without  waiting  for  other  portions  of  the  plant,  and  an 
operating  force  can  be  broken  in  rapidly  on  the  machines  in  operation,  thus  being 
prepared  to  run  the  other  units  as  fast  as  it  is  found  to  be  necessary. 

Boiler  House.  —  The  boiler  house  is  usually  arranged  so  that  the  boilers  are  located 
on  one  or  two  floors,  with  a  basement  beneath  the  lower  boiler  room.  This  arrange- 
ment, however,  is  seldom  found  except  in  the  case  of  large  plants.  Such  a  basement 
is  arranged  for  the  handling  of  ashes,  soot,  the  boiler  feed  pumps,  piping,  fans  for 
forced  draft,  storerooms,  repair  shops,  etc.,  and,  occasionally,  on  the  Continent  of 
Europe,  economizers  are  placed  in  the  basement,  though  in  British  and  American 


18 


STEAM-ELECTRIC    POWER    PLANTS. 


practice  economizers  are  usually  placed  on  the  floor  of  the  boiler  room,  as  is  the  case 
in  the  power  plant  of  the  Manhattan  Elevated  Railroad  and  the  Chelsea  plant  of 
London,  which  are  very  similar.  In  these  instances  the  economizers  are  placed  in  the 
rear  of  each  of  the  two  tiers,  while  in  the  St.  Denis  plant  of  Paris  and  the  plant  of  the 
Glasgow  Corporation  the  economizers  are  placed  on  a  floor  above  the  boilers.  Coal 
bunkers  above  the  boilers  are  more  frequently  found  in  British  and  American  practice, 
while  on  the  Continent  a  coal  storage  house  is  frequently  provided  at  the  side  of  the 


boiler  house,  as  may  be  seen  in  Fig.  6,  which  shows  a  cross-section  similar  to  one  of 
the  twin  municipal  plants  of  Vienna. 

The  smokestacks  are  frequently  located  directly  in  the  boiler  house,  extending 
through  to  the  basement  between  the  boiler  settings.  This  also  is  practically  confined 
to  British  and  American  practice,  for  on  the  Continent  of  Europe  the  smokestack  is 
frequently  placed  several  feet  away  from  the  boiler  house.  This,  however,  may  be 
due,  to  a  certain  extent,  to  the  cheapness  of  land,  but  where  this  is  very  expensive  it 
will  probably  pay  to  carry  the  smokestacks  on  the  columns  from  which  the  coal  bunkers 
are  suspended,  as  has  been  done  in  one  of  the  largest  plants  in  the  world  —  that  of  the 
New  York  Subway  system.  Here  there  are  five  1,200- ton  radial  brick  smokestacks, 
each  of  which  is  supported  on  six  columns,  which  carry  part  of  the  load  of  the  boilers 
and  that  of  the  coal  bunkers.  This  same  arrangement  has  been  adopted  by  the  New 
York  Central  and  Hudson  River  Railroad  Co.  in  their  two  stations  at  Yonkers 
and  Port  Morris,  in  the  vicinity  of  New  York  City.  In  the  above-mentioned  stations 
there  are  two  rows  of  boilers  arranged  on  one  floor  with  a  firing  aisle  between,  the 
smokestack  above  the  firing  aisle  rising  through  the  bunkers  and  dividing  it  in  sec- 
tions, therefore  reducing  the  coal  storage  capacity.  By  having  the  firing  aisles  arranged 
so  that  they  are  at  right  angles  to  the  generating  room,  as  previously  explained,  and  in 


GENERAL    LAYOUT.  19 

common  use  in  turbine  stations,  each  group  of  boilers  may  have  its  own  smokestack, 
as  is  the  case  in  the  Delaware  Avenue  station  of  the  Philadelphia  Rapid  Transit  Co., 
Philadelphia,  Pa.,  or  two  groups  of  boilers  may  have  a  common  smokestack,  as 
with  the  Fisk  Street  station  of  the  Commonwealth  Electric  Co.  of  Chicago,  and  the 
Boston  Edison  station,  diagrammatically  shown  in  Fig.  4.  In  the  diagram  Fig.  4  it  will 
be  noted  that  there  are  three  firing  aisles,  the  center  one  being  common  to  two  rows  of 
boilers  and  the  end  aisles  serving  a  single  row  of  boilers.  Stacks  common  to  two  rows 


FIG.  7. 

of  boilers  are  either  mounted  on  columns,  as  in  the  Fisk  Street  station  in  Chicago, 
where  steel  stacks  are  used,  or  extend  to  the  ground  between  the  boilers,  as  in  the 
Boston  Edison  station,  where  radial  brick  stacks  are  used.  The  space  between  the 
boilers  in  this  latter  case  can  be  utilized  for  the  installation  of  economizers,  should  their 
adoption  be  decided  upon.  Fig.  5  shows  an  alternative  layout  in  diagram,  which 
differs  from  the  above  in  having  only  two  firing  aisles  for  the  same  number  of  boilers. 
This  diagram  shows  a  boiler  room  similar  to  that  of  the  Delaware  Avenue  plant  in 
Philadelphia,  while  the  turbine  room  is  similar  to  that  of  the  St.  Denis  plant  at  Paris, 
France.  In  this  arrangement  each  row  of  boilers  is  served  by  a  separate  chimney. 


20 


STEAM-ELECTRIC    POWER    PLANTS. 


In  some  cases  this  arrangement  is  partially  adopted,  the  double  row  of  boilers  being 
served  by  a  larger  stack  than  the  single  rows.  The  disadvantage  of  this  arrangement 
appears  when  it  is  desired  to  extend  the  plant,  which  becomes  unsymmetrical  from  an 
architectural  point  of  view.  An  example  of  this  construction  is  the  Detroit  (Michigan) 
Edison  Company's  plant  and  the  Marion  (New  Jersey)  plant  of  the  Public  Service  Cor- 
poration. When  separate  chimneys  are  used  for  each  row  of  boilers,  the  appearance  of 
the  plant  may  be  marred  by  the  large  number  of  chimneys  required,  but  this  arrange- 
ment lends  itself  to  suitable  architectural  treatment.  An  advantage  of  this  construction 
is  that  it  extends  the  unit  system  further  than  it  is  usually  carried,  though  on  the  score  of 
expense  the  two  small  chimneys  required  for  the  double  row  of  boilers  cost  slightly 
more  than  would  a  single  chimney,  capable  of  serving  both  rows.  When  the  dampers, 
flues  and  other  items  connected  with  the  structure  are  considered,  however,  it  may 
easily  be  found  that  the  smaller  chimneys  entail  less  expense,  and  the  difference  may 
be  more  than  sufficient  to  make  the  small  chimneys  the  less  costly.  The  arrangement 
shown  in  Fig.  5  also  reduces  the  number  of  bunkers  and  conveyors  required  below  that 
shown  in  Fig.  4,  but  in  extending  the  plant  in  the  latter  case  an  additional  row  of 
boilers  can  be  added,  and  no  additional  bunker  need  be  constructed,  while  in  the  former 
the  addition  of  a  row  of  boilers  requires  an  additional  bunker,  with  its  coal  conveyors. 
An  arrangement  frequently  used  in  Great  Britain  and  the  United  States  is  shown 
in  Fig.  7,  and  a  third  deck  of  boilers  has  been  used  in  some  cases.  This  arrangement 
is  prohibited  by  law  in  France,  where  boiler  houses  are  restricted  to  a  single  story ;  and 


elsewhere  on  the  Continent  this  arrangement,  although  low  in  first  cost  of  building,  is 
not  looked  upon  with  favor,  owing  to  the  comparatively  low  cost  of  land.  Another 
reason  is  that  dynamos  and  engines  used  in  these  countries  have  not  been  of  the 
enormous  size  of  those  used  in  America  until  within  a  recent  date,  when  some 
turbo-generators  of  io,ooo-horse-power  have  been  put  in  operation. 


GENERAL     LAYOUT.  21 

The  cross-sections  shown  in  Figs.  7  and  8  represent,  in  the  first  case,  a  two-story 
boiler  house  parallel  with  the  generator  room,  and  in  the  second  case  a  boiler  room  at 
right  angles  with  the  generator  room.  It  will  be  noted  that  the  bunker  capacity  in  the 
former  case  is  larger  than  in  the  latter,  and  when  a  single-story  boiler  room  is  used, 
similar  to  Fig.  7,  the  bunker  capacity  is  retained.  Fig.  8  is  a  cross- section  of  a  plant, 
the  plans  of  which  are  shown  in  Figs.  4  and  5,  the  generator  room,  however,  being 
slightly  different. 

Boilers  up  to  6,500  square  feet  of  heating  surface  are  usually  set  two  in  a  battery, 
while  those  of  larger  size  are  preferably  set  as  individual  units.  The  space  between  a 
pair  of  boilers  or  at  the  side  of  a  battery  should  be  at  least  five  feet,  to  allow  room  for 
dusting  the  tubes  and  cleaning.  The  firing  aisles  are,  of  necessity,  of  sufficient  width 
to  permit  the  withdrawal  of  the  tubes,  and  should  be  from  two  to  three  feet  wider  than 
the  length  of  the  longest  tube  to  be  handled.  From  six  to  eight  feet  is  required  above 
the  boilers,  to  permit  the  installation  of  the  large  radius  bends  required  in  up-to-date 
steam-pipe  construction,  and  to  allow  sufficient  space  for  the  walkways  required  to 
give  access  to  the  various  valves.  From  a  commercial  standpoint  it  is  desirable  to  keep 
the  boiler  room  as  low  as  possible  in  total  height,  but  at  the  same  time  efficient  opera- 
tion cannot  be  attained  unless  sufficient  space  is  provided  to  give  free  access  to  all  parts 
of  the  apparatus.  As  an  illustration  of  the  wide  difference  in  the  views  of  different 
designers,  in  the  Interborough  power  plant  in  New  York  the  height  of  the  boiler  room 
from  basement  floor  to  the  peak  of  the  roof  is  125  feet,  and  in  the  St.  Denis  plant  at 
Paris  this  height  is  65  feet.  In  both  cases  there  is  a  basement,  one  floor  of  boilers,  one 
economizer  floor  and  coal  bunkers.  The  former  plant  uses  the  regular  stationary 
Babcock  &  Wilcox  boiler  of  6,000  square  feet  heating  surface  and  the  bunkers  are 
above  the  economizer  floor.  In  the  French  plant  the  marine  type  Babcock  &  Wilcox 
boiler  is  used,  having  4,000  square  feet  of  heating  surface,  and  the  coal  bunker  is  sus- 
pended between  the  economizer  floors  or  galleries. 

Special  attention  is  called  to  Fig.  6,  which  represents  a  typical  Continental  power 
plant,  a  very  low  boiler  room,  with  a  basement  and  a  monitor  skylight  over  the  firing 
aisle,  for  supplying  light  and  ventilation,  and  a  coal  storage  room  alongside  of  the  boiler 
room,  from  which  the  coal  is  wheeled  in  cars  or  wheelbarrows  to  the  firing  aisle. 

Engine  House.  —  Where  other  considerations  will  permit,  it  is  a  good  plan  to  locate 
the  engine  room  on  the  north  side  of  the  building,  and  make  the  north  slope  of  the  roof 
a  large  skylight;  south  of  the  equator  this  arrangement  should  be  reversed.  The 
advantage  of  this  arrangement  arises  from  the  better  illumination  of  the  room,  which 
will  be  much  cooler  in  warm  weather,  owing  to  the  fact  that  it  will  not  be  exposed  to  the 
*  sun  shining  in  the  large  windows.  While  this  arrangement  will  add  considerably  to 
the  comfort  of  the  engine  room,  it  will  cause  but  a  very  slight  addition  to  the 
unavoidable  heat  in  the  boiler  room. 

The  engine  house  or  generating  room  usually  occupies  a  single  operating  floor  with 
a  basement  below,  having  the  main  generating  sets  and  exciters  on  the  former,  while 
the  basement  is  best  adapted  to  the  condenser,  the  necessary  auxiliary  pumps  and 


STEAM-ELECTRIC   POWER    PLANTS. 

piping.     Also  it  is  preferable  to  locate  here  the  cables  leading  from  the  generators  to 
the  switchboard,  storage  batteries,  etc. 

In  horizontal  turbine  plants  the  condensing  outfit  may  be  placed  between  the  foun- 
dation of  the  turbine  unit,  while  with  the  vertical  turbine  the  turbine  is  frequently  set 
directly  upon  the  lowest  floor,  the  condenser  being  placed  beside  it,  but  often  serving 
as  a  base  for  the  turbine,  in  which  case  the  lower  floor  becomes  the  main  operating 
floor  (see  Figs.  4  and  7),  and  a  gallery  is  constructed  around  the  generating  units,  there 
being  no  basement  below  the  main  operating  room.  Where  horizontal  turbines  are  in 
use  care  should  be  taken  to  provide  large  openings  in  the  floor  to  facilitate  the  handling 
of  condensers  and  auxiliaries  in  the  basement,  by  a  crane,  —  a  practice  which  has  been 
adopted  in  the  Carville  plant  in  Newcastle,  the  St.  Denis  plant,  Paris,  and  the  Chelsea 
plant  of  London.  Where  vertical  turbines  are  used  and  a  gallery  provided  around 
the  generators,  the  auxiliaries  are  placed  around  the  turbine  itself,  below  the  gallery, 
provision  being  made  that  the  auxiliaries  may  be  handled  by  the  crane,  and  when 
horizontal  turbines  are  installed  similar  provisions  should  be  made.  In  fact  it  is 
extremely  important  that  all  the  auxiliaries  should  be  accessible,  and  such  galleries  as 
obstruct  the  use  of  the  crane  should  be  made  in  sections  which  can  be  removed  when 
occasion  arises. 

The  operating  galleries  should  be  designed  to  give  access  to  all  parts  of  the 
machinery,  and  it  is  desirable  to  have  a  gallery  along  the  division  wall  at  the  level  of 
the  boiler  floor,  to  which  access  is  given  by  doorways ;  this  gallery,  being  connected  to 
the  machine  galleries  by  stairways,  or  bridges,  furnishes  a  rapid  method  of  getting 
from  one  machine  to  another,  without  the  necessity  of  climbing  around  the  intervening 
machines.  It  is  also  a  good  plan  to  carry  this  gallery  across  the  room  to  the  switch- 
board galleries,  on  the  opposite  side,  at  the  ends,  and  at  an  intermediate  point  in  a 
large  plant.  This  gallery  will,  in  fact,  be  like  the  bridge  of  a  ship  and  supplies  an 
elevated  position  whence  the  watch  engineers  can  observe  the  entire  plant. 

The  above-mentioned  arrangement  applies  more  particularly  to  vertical  turbine 
plants.  Where  horizontal  turbines  are  used,  there  is  usually  a  floor  in  the  turbine 
room,  level  with  the  boiler  floor,  and  the  galleries  on  such  machines  are  but  slightly 
above  the  floor  level,  in  fact  some  very  large  units  have  no  galleries  whatever;  for  in- 
stance, the  10,000  horse-power  Brown-Boveri-Parsons  turbines,  in  the  Rhenish- West- 
phalia power  plant  at  Essen,  Germany,  which  is  handled  entirely  from  the  floor. 
When  horizontal  engines  are  used  there  are  practically  no  galleries,  light  ornamental 
ladders  (usually  supplied  by  the  engine  builders)  giving  access  to  all  points  too  high  to 
be  reached  from  the  floor.  With  vertical  engines  a  gallery  on  the  division  wall  should 
be  at  the  height  of  the  galleries  around  the  cylinders  and  connected  to  it  by  bridges. 
The  horizontal-vertical  engines  are  usually  set  in  a  row  in  the  middle  of  the  room,  and 
the  upper  galleries  of  the  machines  are  connected,  and  if  desirable  light  bridges  can  be 
used  to  connect  the  machine  galleries  with  the  galleries  around  the  room. 

When  surface  condensers  are  to  be  used  it  is  essential  that  means  be  provided  for 
handling  the  condenser  heads,  and  sufficient  room  must  be  allowed  to  permit 
the  replacement  of  the  tubes,  which  must  be  carefully  handled.  The  auxiliary 


GENERAL    LAYOUT.  23 

machinery  and  exciters  must  be  placed  so  as  to  secure  short  pipe  runs,  and  at  the  same 
time  be  so  located  that  there  is  enough  room  to  permit  all  parts  to  be  properly  looked 
after  in  operation,  without  exposing  the  men  to  the  danger  of  being  caught  by  parts 
in  motion.  Guard  rails  should  be  provided  at  all  dangerous  points. 

It  is  a  good  plan  to  arrange  the  plant  so  that  the  necessary  cables  and  steam  pipes 
do  not  cross  each  other;  that  is,  the  conductors  from  the  generators  should  leave  the 
machines  on  the  side  away  from  the  boiler  room,  and  the  condensers  and  their  pumps 
should  preferably  be  located  where  they  do  not  interfere  in  any  way  with  the  layout  of 
the  duct  lines;  all  steam  and  exhaust  pipes  being  kept,  so  far  as  possible,  below  the 
floor,  in  order  that  the  general  appearance  of  the  room  may  not  be  spoiled. 

In  the  most  modern  plants  the  practice  is  to  install  a  central  oiling  system.  When 
this  is  done  it  is  advisable  to  place  the  filters,  storage  and  pressure  tanks,  together  with 
the  pumps  (when  gravity  tanks  are  not  used),  in  a  separate  room  of  fireproof  construc- 
tion, the  only  connection  to  the  main  plant  being  by  means  of  the  piping.  In  some 
cases  this  precaution  is  entirely  neglected,  and  in  other  cases  only  the  main  storage 
tanks  are  located  outside:  the  pressure  tanks  and  filters  being  located  in  the  operating 
room,  or  on  the  roof  when  gravity  tanks  are  employed. 

In  placing  the  machinery  a  great  deal  of  study  is  required  in  order  that  the  room 
may  be  utilized  to  the  best  advantage,  without  overcrowding.  Plenty  of  room  is 
desirable,  but  at  the  same  time  where  land  is  costly  it  is  desirable  to  use  it  all  to  the  best 
advantage  without  waste.  This  principle  has  been  closely  studied  in  Great  Britain 
and  the  United  States,  while  in  Continental  Europe  a  great  deal  of  room  is  frequently 
wasted,  o\ving  to  the  manner  in  which  the  machines  are  located;  this,  however,  is  due 
to  the  fact  that  land  values  are  not  so  important. 

In  the  plants  and  arrangements  above  mentioned  the  condensers  were  located  either 
in  the  basement  or  on  the  main  operating  floor.  There  are,  however,  some  plants  in 
existence  in  which  a  separate  building  or  room  is  provided  for  the  condensers  and 
their  pumps;  the  plant  of  the  Glasgow,  Scotland,  Corporation  Tramways,  for  instance. 
In  this  plant,  vertical  three-cylinder  compound  engines  are  employed  and  surface 
condensers  are  used.  The  main  units  are  set  close  together,  and  in  order  to  keep 
down  the  width  of  the  engine  room,  where  a  heavy  crane  was  required,  the  condensers 
were  placed  in  a  separate  room,  parallel  with  the  engine  room,  where  they  were  covered 
by  a  short  span  crane  of  smaller  capacity.  This  makes  it  very  easy  to  look  after  the 
condensers,  but  is  not  economical  in  the  ground  area  occupied.  In  some  cases  a  central 
condensing  plant,  of  the  barometric  or  injector  type,  is  employed;  the  practice  being 
in  such  cases  to  install  the  condenser  outside  the  building,  while  the  pumps  serving 
it  are  inside.  These  condensers  are  supported  by  a  skeleton  steel  frame  and  the  exhaust 
pipes  from  a  number  of  engines  (often  at  a  considerable  distance)  are  led  to  them. 

Cooling  towers  are  of  two  types,  forced  and  natural  draft,  and  the  location  of  the 
former  can  be  made  to  suit  local  conditions,  but  the  latter  must  be  so  situated  that  it  is 
not  sheltered  or  protected  by  adjacent  buildings.  Cooling  basins  or  ponds  are  also 
employed,  in  which  the  water  is  sprayed  into  the  pond  by  a  number  of  jets.  Apparatus 
of  this  character  is  used  where  the  quantity  of  circulating  water  required  for  the  con- 


STEAM-ELECTRIC    POWER    PLANTS. 


GENERAL    LAYOUT.  25 

densers  is  larger  than  can  be  obtained  from  local  sources  of  supply  at  reasonable  cost. 
Small  towers  are  sometimes  located  on  the  roof  of  the  building,  and  the  water  circulates 
through  the  condenser  by  gravity  and  is  returned  to  the  tower  by  the  pump.  Forced 
draft  towers  are  provided  with  a  small  shed  in  which  the  motor  for  driving  the  fan  is 
sheltered. 

Switching  Room.  — Another  important  consideration  in  power  plant  design  is  that 
of  the  switchboard.  In  large  power  houses  an  annex  to  the  generating  room  for 
switching  and  measuring  purposes  may  be  very  convenient,  but  where  this  space  is 
not  available  a  part  of  the  generating  room  may  be  used,  care  being  taken  not  to 
locate  the  switchboard  on  the  boiler-house  side  of  the  plant,  the  high-tension  lines 
and  steam  pipes  being  liable  to  interfere  with  each  other.  Both  should  be  carried 
under  the  engine-room  floor  and  kept  well  apart.  In  plants  of  smaller  capacity  the 
end  wall  of  the  generating  room  is  usually  large  enough  to  accommodate  the  bus-bars 
and  switching  system,  which  when  possible  are  placed  there,  as  is  the  case  with  the  five 
stations  of  the  street  railway  system  of  the  City  of  Hamburg,  Germany,  but  with  plants 
of  larger  capacity,  when  this  space  is  seldom  large  enough  to  accommodate  the  bus- 
bar and  switching  system,  a  space  at  the  side  of  the  generating  room  may  be  utilized 
for  this  purpose.  The  main  bus-bars  may  be  located  below  the  floor  level  of  the 
engine  room,  but  the  controlling  switches  should  preferably  be  placed  in  the  gallery, 
from  which  the  generating  room  is  easily  overlooked.  The  Elevated  Railroad  power 
house  at  East  74th  Street,  the  Subway  Railroad  power  house  at  West  59th  Street, 
both  of  New  York  City,  the  Chelsea  plant  in  London,  and  the  Carville  plant  in  New- 
castle, England,  all  have  their  switchboards  arranged  in  this  manner.  The  end  wall 
may  even  be  utilized  for  switchboard  purposes  in  the  larger  plants  by  building  it  in 
several  tiers.  This  has  been  done  in  the  Waterside  station,  No.  i  of  the  New  York 
Edison  Company.  Figs.  6  and  7  show  a  station  with  an  annex  built  for  switching 
purposes.  This  annex  may  run  the  entire  length  of  the  building,  as  is  the  case  with 
the  Public  Service  Corporation  of  New  Jersey,  and  the  Potomac  Electric  Power 
Company  of  Washington,  B.C.,  while  the  St.  Denis  plant  of  Paris,  and  the  twin 
municipal  plant  of  Vienna  have  their  annex  constructed  along  the  lines  of  that 
shown  in  Figs.  5  and  6. 

Care  should  be  used  to  avoid  crowding  of  the  switching  compartment.  Frequently 
this  branch  of  power  plant  design  is  considered  of  small  importance;  this,  however, 
is  an  entirely  mistaken  idea;  on  the  contrary,  the  switching  room  with  its  wiring  system 
may  be  said  to  be  the  pulse  of  the  entire  electrical  equipment,  just  as  the  steam-pipe 
system  is  that  of  the  mechanical  equipment.  The  crowding  of  the  switching  apparatus 
into  a  corner  of  the  power  plant  can  only  be  looked  upon  as  poor  policy.  The 
Swiss,  usually  acknowledged  leaders  in  switchboard  installation,  give  us  examples  of 
where  the  floor  space  occupied  by  the  switching  room  is  more  than  that  of  the  generating 
room  itself.  The  Swiss  plants,  however,  are  usually  hydraulic  plants,  and  an  example 
may  here  be  of  interest.  The  switching  house  of  the  plant  "Obermatt,"  of  the  City  of 
Lucerne,  covers  an  area  of  almost  three-quarters  of  the  generating  room,  but  as  the 


26  STEAM-ELECTRIC    POWER    PLANTS. 

switching  house  occupies  three  floors,  the  floor  space  is  more  than  twice  that  of  the 
generating  room. 

In  speaking  of  the  generating  room,  the  floor  or  ground  area  occupied  alone  has 
been  considered,  the  height  being  dependent  upon  architectural  considerations  and 
the  type  of  machinery  used.  Horizontal  engines  and  turbines  can  be  installed  within 
a  low  building,  while  vertical  engines  and  turbines  require  a  higher  roof.  The  height 
of  the  boiler  room  has  already  been  mentioned;  for  architectural  reasons  the  engine 
room  is  frequently  made  of  equal  height,  although  by  so  doing  the  cost  of  the  walls  and 
steel  framing  is  considerably  increased.  From  an  engineering  standpoint  the  height 
of  the  engine  room  is  fixed  by  the  height  required  under  the  crane  to  handle  the 
machinery. 

Coal  Storage  Plant.  — As  has  been  stated  in  a  previous  chapter  an  additional  storage 
capacity  for  coal  should  be  provided  besides  the  bunkers  above  the  boilers,  as  they  are 
of  comparatively  small  capacity,  when  the  output  of  the  plant  is  taken  into  consideration. 

Strikes,  either  at  the  mines  or  the  transportation  companies,  are  liable  to  occur  at 
any  time,  so  it  is  often  considered  advisable  to  arrange  for  capacity  enough  to  carry  the 
plant  several  weeks.  It  is  advisable  also  that  this  coal  storage  plant  should  be  placed 
as  near  to  the  power  station  as  is  possible,  and  a  suitable  method  for  conveying  the  coal 
from  the  piles  to  the  bunkers  be  provided.  The  cars  may  run  on  trestles  at  the  side  of 
the  boiler  house,  and  dump  the  coal  directly  on  the  ground  beneath  the  trestle  where 
it  is  stored,  or  the  cars  may  be  dumped  in  hoppers  from  which  it  is  conveyed 
and  deposited  in  coal  piles,  a  similar  system  being  used  where  the  coal  is  unloaded 
from  barges  and  conveved  to  its  storage.  It  is  customarv  in  American  and  British 

O 

practice  to  provide  for  the  coal  storage  capacity  in  the  bunkers  beneath  the  boiler- 
house  roof;  while  on  the  Continent  of  Europe  a  separate  building  is  provided.  It  can 
be  easily  seen  that  the  storage  capacity  of  the  bunkers  is  limited,  and  in  order  that 
capacity  enough  to  last  some  time  shall  be  had  the  usual  American  practice  is  to  dump 
the  coal  in  an  open  field  where  it  is  possible  to  do  so.  This  has  been  necessitated  by 
the  size  of  American  plants,  while  in  European  plants  capacity  enough  to  run  the  plants 
several  weeks  is  easily  obtainable  in  buildings,  which  are  built  by  the  side  of  the  boiler 
house,  as  illustrated  in  Fig.  6,  though  there  are  some  cases  wh^re  the  coal  is  stored  in 
the  open  at  the  side  of  the  boiler  house. 

Auxiliary  Buildings.  —  Under  auxiliary  buildings  we  may  consider  those  buildings 
which  are  necessary  to  facilitate  the  successful  operation  of  the  plant,  consisting  of 
offices,  repair  shops,  storehouses  and  pumping  stations,  while  in  cases  where  the  plant 
is  situated  in  the  country,  residences  are  provided  for  the  superintendent  of  the  plant 
and  the  main  operating  force.  This  practice,  however,  is  practically  confined  to  Europe, 
while  in  America  all  of  the  machinery  is  generally  placed  under  one  roof,  and  as  the 
large  plants  are  in  or  near  the  cities  the  operating  force  may  live  in  the  immediate 
neighborhood.  The  arrangement  of  the  auxiliary  buildings  of  two  European  plants 
mav  here  be  of  interest.  The  site  of  the  Carville  power  station  in  Newcastle,  Eng- 


COAL    STORAGE.  27 

land,  banked  on  one  side  by  the  river  Tyne,  and  on  the  other  by  the  railroad  from 
which  sidings  run  directly  to  the  plant,  has  upon  it  a  number  of  auxiliary  buildings, 
such  as  pump  house,  office  building,  a  store  and  fitting  shop,  blacksmith  shop  and 
accommodation  for  workmen,  a  special  construction  office  and  joiners  or  carpenters 
shop,  while  a  special  reserve  water  tank  and  a  sub-station  are  also  on  the  same  plot. 
The  tracks  from  the  railroad  are  so  arranged  that  a  car  may  be  run  directly  to  any  of 
the  prominent  buildings  (see  Fig.  9). 

The  twin  municipal  plant  of  Vienna  is  situated  on  a  plot  by  the  Danube  Canal, 
the  siding  from  the  railway  running  directly  between  the  two  plants  (see  Chapter  X). 
Situated  on  the  plot  near  the  main  buildings  are  two  pumping  stations,  one  large  and  one 
small,  three  pumping  pits,  a  reservoir,  an  office  building,  residence  for  the  superintendent 
and  one  for  the  main  operating  force,  and,  as  the  plant  is  situated  outside  the  city,  there 
is  a  canteen  for  the  working  force.  The  entire  plant  is  surrounded  by  grass  plots  with 
graveled  walks  and  a  number  of  shade  trees  have  been  set  out,  not  only  with  the  idea 
of  beautifying  the  surroundings  of  the  plant,  but  to  serve  a  utilitarian  purpose  in  pre- 
venting the  dust  which  would  otherwise  be  swept  into  the  plant  were  the  earth  bare. 
The  plant  is  also  surrounded  by  a  high  picket  fence. 

COAL    STORAGE.* 

Introductory. — The  fuel  question  is  one  of  the  live  subjects  before  the  power  plant 
manager;  the  plant  cannot  run  without  fuel  and  the  cost  of  this  is  the  largest  single  item 
in  the  operating  account.  The  cost  of  the  coal  per  ton,  as  taken  from  the  bill,  is  not 
the  total  cost  of  that  amount  of  coal,  for  this  only  includes  its  delivery  in  cars  or  boats 
at  the  power  plant,  where  it  has  to  be  unloaded,  conveyed  to  the  fire  room,  placed  on 
the  grate  and  the  ashes  removed  from  the  building  and  disposed  of. 

The  quantity  of  coal  burned  is  from  ten  to  twenty-five  times  the  weight  of 
the  resulting  ashes,  and  for  this  reason  proximity  to  a  point  where  coal  can  be  secured 
with  the  minimum  amount  of  handling  is  of  more  importance  than  ability  to  dispose 
of  the  ashes.  In  any  event  it  is  desirable  to  avoid  carting  either  coal  or  ashes,  since 
such  procedure  means  additional  handling  and  its  attendant  expense. 

As  plants  increase  in  size  the  importance  of  a  reserve  supply  of  coal  becomes  more 
and  more  evident ;  for  the  small  plant  whose  consumption  is  limited  to  five  or  ten  .tons 
of  coal  per  day,  one  or  two  carloads  is  often  considered  a  big  supply  on  hand,  while 
in  the  plant  whose  daily  requirements  run  from  six  hundred  to  a  thousand  tons,  a  large 
reserve  is  necessary. 

The  uncertainty  of  the  coal  supply  is  due  to  many  causes,  strikes  in  the  mines  of 
from  a  few  days'  to  a  number  of  months'  duration  have  often  occurred;  and  in  some 
cases  these  labor  troubles  have  been  sufficient  in  magnitude  practically  to  stop  the 
mining  of  coal.  All  transportation  service  is  subject  to  interruptions  of  a  more  or  less 
serious  character  from  storms,  floods  and  strikes;  these  last,  however,  have  not  been 
frequent  in  late  years,  but  a  number  of  railroads  have  had  considerable  trouble  with 

*  See  author's  original  article  in  Power,  April,  1907. 


28 


STEAM-ELECTRIC    POWER    PLANTS. 


freight  handlers  in  some  localities.  Where  railroads  are  depended  upon  for  coal  sup- 
plies, the  first  sign  of  labor  troubles  at  the  mines  is  the  signal  for  them  to  seize  all  the 
coal  in  transit  on  their  rails,  and  until  their  own  stores  are  filled  to  the  limit  there  is 
little  chance  for  an  outsider  to  secure  any  quantity  of  coal. 

Since,  except  in  a  few  instances,  it  is  impossible  for  the  coal  consumer  to  have  abso- 
lute control  of  his  supply  from  the  mine  to  the  fire  room,  it  is  absolutely  necessary  to 


ffflmi 


FIG.  i.      Coal  and  Ash  Handling  Scheme  with  Browning  Travelling  Crane. 

adopt  such  measures  as  will  protect  his  interest  during  all  contingencies,  and  the  only 
method  by  which  continuity  of  plant  operation  can  be  insured  under  all  circumstances 
is  by  the  establishment  of  a  coal  storage  plant  of  sufficient  size  to  carry  the  plant  over 
any  stoppage  in  the  receipt  of  coal. 

In  some  plants  the  coal  bunkers  alone  are  depended  upon  as  a  reserve,  while  in 
other  cases  they  have  been  augmented  by  storage  plants  designed  for  the  purpose.  A 
fuel  storage  plant  of  any  magnitude  involves  a  considerable  investment  in  machinery, 
and  in  addition  a  large  amount  of  money  is  tied  up  in  the  coal  pile.  The  interest  on 
this  money  and  the  operating  costs  of  the  plant  add  continually  to  the  fuel  bill,  but 
to  offset  this  the  insurance  value  of  the  plant  in  times  of  trouble  is  beyond  computation. 

Exposed  Coai  Piles. —  Most  coal  storage  plants  have  the  piles  exposed  to  the  weather, 
and  for  practical  reasons  it  is  essential  that  a  portion,  if  not  all,  of  the  daily  supply  be 
handled,  in  .order  10  keep  the  machinery  in  shape,  and  for  other  reasons,  as  will  appear 
below.  Coal  stored  in  the  open  or  under  cover  loses  a  portion  of  its  heating  value,  this 


COAL    STORAGE. 


29 


loss,  in  fact,  being  due  to  slow  chemical  changes  which  start  as  soon  as  coal  is  exposed 
in  the  breast  at  the  mine  and  continue  until  it  is  burned.  These  losses  are  greatest 
with  bituminous  coals;  the  anthracite  coals  depreciate  less  rapidly.  The  losses  are 


FIG.  2.      Coal  and  Ash  Handling  System,  the  Rhode  Island  Suburban  Railway,  Providence. 

higher  in  warm  weather  and  in  the  tropics,  and  are  due  in  part  to  the  coal  giving  up 
its  gases,  which  in  some  cases  have  a  considerable  thermal  value.  These  losses  are 
slight  when  the  coal  is  fresh,  but  increase  rapidly  as  the  coal  ages. 

Spontaneous  Combustion.  —  Coal  pile  fires  are  not  of  infrequent  occurrence,  although 
it  is  very  rare  that  they  are  chronicled.  Their  cause  is  somewhat  obscure,  but  they  occur 
more  frequently  in  bituminous  coal  which  contains  considerable  sulphur,  in  the  form  of 
iron  pyrites,  though  all  coals  of  a  friable  nature  are  liable  to  spontaneous  combustion. 
There  is  considerable  difference  of  opinion  in  regard  to  the  cause ;  moisture  is  by  some 
considered  to  retard  ignition,  but  wet  coal  in  compact  masses  has  been  known  to  fire  spon- 
taneously. Ventilation  sufficient  to  evaporate  the  water  and  keep  the  heat  of  the  pile 
down  is  probably  the  best  method  of  overcoming  such  trouble,  but  restricted  or  insuffi- 
cient ventilation  is  liable  to  increase  the  trouble.  Such  fires  are  just  as  liable  to  occur 
in  coal  stored  under  cover  as  in  the  open,  but  wet  coal  containing  considerable  pyrites 
will  ignite  if  stored  long  enough  to  allow  of  heating.  Such  fires  are  discoverable  by 
the  odor  of  the  gases,  and  difficulty  in  breathing  at  such  portions  of  the  pile  and  by  the 
heating  of  the  coal.  This  last  can  be  tested  by  driving  pipes,  down  which 
thermometers  can  be  lowered  and  the  temperature  taken,  or  in  winter  by  snow  melting 
on  the  pile.  It  is  impossible  to  fight  such  fires  by  water,  unless  the  whole  pile  can  be 
flooded  and  the  entire  air  supply  cut  off  in  this  way,  because  the  fire  cokes  the  coal 
adjacent  to  it  previous  to  its  burning,  forming  a  roof  which  sheds  the  water,  most  of 
which  is  usually  evaporated  before  it  gets  so  far  down  in  the  pile. 


STEAM-ELECTRIC    POWER    PLANTS. 


Pointed  perforated  iron  pipes  can  be  driven  into  the  pile,  and  water  forced  to  the 
fire  through  them,  but  the  most  complete  method  is  to  remove  the  coal  over  the  fire 
and  then  attack  it. 

Another  trouble  with  exposed  coal  piles  and  railroad  shipments  occurs  in  winter 
when  the  coal  often  arrives  frozen  solid  in  the  car,  and  the  unloading  tracks  must  be 
equipped  with  steam  pipes  and  outlets  for  thawing  purposes. 

From  the  above  it  may  be  seen  that  the  storage  question  is  not  simple,  and  must 
be  handled  with  a  full  understanding  of  the  many  trials  and  tribulations  that  ensue. 

Character  of  Storage  Plant.  —  The  general  arrangement  and  the  plan  required  for 
coal  storage  depend  upon  local  conditions,  and  the  concerns  building  this  class  of 

machinery  are  prepared  to  submit  designs 
for  plants  of  any  desired  capacity,  when 
they  are  furnished  with  ground  plans  show- 
ing the  area  to  be  covered  and  its  contour. 
Some  plants  require  level  ground  or  expen- 
sive grading,  while  other  machines  can  be 
installed  with  but  a  slight  amount  of  grad- 
ing. The  character  of  the  plant  will  depend 
in  part  upon  the  method  by  which  the  coal 
is  received  and  delivered;  in  some  places 
cars  alone  are  received,  in  others,  boat  coal 
only,  and  occasionally  both  methods  are 
available.  Coal  is  also  transported  to  the 
power  plant  by  conveyors  and  in  notable 
instances  it  must  be  reloaded  in  barges  to 
reach  the  power  house. 

In  Continental  plants  the  coal  storage 
is  generally  located  alongside  the  boiler 
house  and  is  usually  covered,  or  roofed  in, 
and  the  coal  is  brought  into  the  firing  room 
by  small  cars.  But  in  a  few  of  the  recent 
plants  American  practices  have  been  fol- 
lowed, overhead  bunkers  and  conveyors 


FIG.  3.     Coal  Conveying  System,  Willis- 
den  Plant,  London. 


being    introduced    and  the   coal  spouted  down   to   the   boilers. 

Description  of  Various  Storage  Plants.  —  The  coal  storage  .plant  of  the  Edison 
Electric  Illuminating  Co.  of  Boston,  Mass.,  presents  a  very  interesting  method  of  treat- 
ment. At  this  plant  the  fuel  is  delivered  in  large  barges,  carrying  over  1,000  tons  eachr 
and  two  channels  have  been  dredged  out  and  wharves  built,  on  both  sides  of  which 
the  barges  can  be  moored.  On  the  wharf  are  mounted  two"  unloading  towers,  a  small 
one  installed  at  the  time  the  original  power  station  was  built,  and  a  second  tower  added 
at  the  time  the  turbine  station  was  built.  There  is  room  for  an  additional  coal  tower 


COAL    STORAGE. 


on  the  pier,  which  will  be  added  when  the  extension  of  the  station  necessitates  such 
addition  to  the  handling  capacity.  The  first  tower  requires  two  operators,  and  is 
equipped  with  a.  one-ton  bucket,  making  one  trip  per  minute.  The  second  tower 


FIG.  4.     "  Brownhoist  "  Gantry  Crane  with  Cantilever  Extension  at  the  L  Street  Plant, 

Boston. 

requires  but  one  operator,  and  can  unload  from  either  side  of  the  pier;  it  is  equipped 
with  a  one  and  one-half  ton  grab-bucket  which  can  make  three  trips  per  minute. 

The  coal  is  transported  to  the  coal  storage  yard  by  Robins  belt  conveyors,  being 
deposited  along  one  side  of  the  yard  from  the  conveyor  trestle.  The  storage  yard  is 
covered  by  a  bridge  tramway,  which  distributes  the  coal  over  the  yard  or  redeposits 
it  on  the  conveyor,  which  can  be  reversed  for  transporting  the  coal  to  the  bunkers. 
The  storage  capacity  of  this  plant  is  about  100,000  tons  of  coal. 

The  New  York  Edison  Company  has  a  storage  plant  at  Shadyside,  N.J.,  as  pre- 
viously mentioned,  where  facilities  are  provided  for  the  storing  of  50,000  tons  of  bitu- 
minous coal  and  100,000  tons  of  anthracite.  This  arrangement  is  peculiar,  owing 
to  the  fact  that  the  storage  yard  is  located  a  considerable  distance  from  any  power 
plant  of  this  company,  the  reason  being  that  New  York  City  ground  is  too  expensive 
for  this  purpose,  and  likewise  because  railroad  connections  could  not  be  made  to  any 
of  the  plants.  The  site  chosen  for  the  storage  plant  permits  of  connection  with 


32  STEAM-ELECTRIC    POWER    PLANTS. 

several   railroads,    and   arrangements   are   made   by   which   anthracite   coal  can  be 
received  either  by  car  or  by  boat.     The  bituminous  coal  is  received  entirely  by  boat, 


FIG.  5.    Plan  of  the  New  Coal  Storage  Plant  of  the  New  York  Edison  Company  at 

Shadyside,  NJ. 

and  both  kinds  of  coal  must  be  reloaded  into  boats  for  transportation  to  the  stations 
of  the  company  in  New  York  City.  This  plant  was  designed  by  the  Dodge  Coal 
Storage  Company  of  Philadelphia,  Pa. 

The  bituminous  pile  is  covered  by  a  traversing  bridge  equipped  with  a  two-ton  clam- 


FIG.  6.     Dodge  Traversing  Gantry  Bridge,  Coal  Storage  Plant  at   Shady  Side,  New   York 

(Engineering  Record). 

shell  bucket,  which  unloads  from  boats  to  the  pile  or  from  the  pile  to  boats,  the  front 
tower  in  which  the  operator  is  stationed  being  provided  with  suitable  loading  chutes. 


COAL    STORAGE. 


33 


Anthracite  coal  can  be  unloaded  from  boats  by  a  steeple  tower  with  a  one  and 
one-half  ton  grab-bucket,  which  delivers  to  a  reversible  belt  conveyor,  by  which  the 
coal  is  transported  to  a  hopper,  whence  it  passes  to  the  trimming  bridges  spanning 
the  piles.  Railroad  coal  is  dumped  into  a  track  hopper  from  which  it  passes  to  the 
trimmers.  The  anthracite  piles  are  of  the  well-known  Dodge  circular  type,  and  a 
reloading  sweep  traveling  on  semicircular  tracks  is  used  for  taking  the  coal  from  the  piles 
to  a  hopper,  through  which  it  reaches  the  belt  convey  or  leading  to  the  steeple  tower,  which 
is  equipped  with  a  chute  for  loading  boats.  Five-ton  weighing  hoppers,  in  duplicate, 


[<_  00- L-W— $j  I 


FIG  7. 


Steeple  Loading  and  Unloading  Tower  with  Weighing  Hopper,  Shady  Side  Coal 
Storage  Plant  of  the  New  York  Edison  Co.  (Engineering  Record]. 


are  provided  in  the  towers,  by  which  all  coal  can  be  weighed  upon  its  receipt  and  ship- 
ment. 

The  accompanying  illustrations  will  serve  to  give  a  very  comprehensive  idea  of 
this  coal  storage  plant. 

At  the  plant  of  the  Metropolitan  Electric  Supply  Company,  London,  England, 
a  coal  hopper  has  been  built  below  the  track  on  which  coal  is  received.  Over  this 
hopper  is  placed  a  Bennis  rotary  tipping  device  in  which  the  coal  cars,  after  being 
clamped,  can  be  turned  completely  over,  the  coal  falling  into  the  hopper,  from  which 
conveyors  transport  it  to  the  bunker  in  the  boiler  room  (see  Fig.  3). 


34 


STEAM-ELECTRIC    POWER    PLANTS. 


On  the  Continent  of  Europe  a  great  deal  of  hand  labor  is  employed  in  coaling  plants 
for  instance,  at  the  Barmbeck  plant,  Hamburg,  Germany,  the  coal  is  received  in  barges, 
and  is  shoveled  into  buckets;  these  have  a  trolley  attached  to  the  bail  and  are  lifted 
from  the  barge  by  a  traveling  revolving  crane  or  "whirley,"  which  places  the  trolley 
on  an  inclined  track,  down  which  it  runs  into  the  storeroom,  dumping  at  a  determined 


FIG.  8.     Coal  and  Ash  Handling  System,  Williamsburg  Plant,  Brooklyn. 

point  and  passing  on  around  the  loop,  and  back  to  a  point  where  it  can  be  reached 
by  the  crane.  There  are  six  of  these  loops  alongside  of  each  other,  and  the  crane 
can  take  or  place  buckets  on  any  one  of  them.  The  storage  capacity  is  about  6,000 
tons.  The  coal  is  loaded  by  hand  in  three-wheeled  cars,  by  which  it  is  taken  to  the  fire 
room,  and  is  shoveled  from  the  car  into  the  furnace. 

A  novel  system,  involving  much  hand  labor,  both  in  the  receipt  of  coal  and  in  firing 
with  its  attendant  expense,  is  exemplified  by  the  Vienna  twin  municipal  plant  in 
Austria.  The  coal  is  brought  in  by  cars  on  a  railroad  siding  running  between  the  two 
plants;  these  are  passed  over  a  scale  and  are  weighed;  they  are  then  placed  on  a  transfer 
table  by  means  of  which  they  are  transported  laterally  to  either  of  the  two  plants.  From 
the  transfer  table  the  cars  pass  to  tracks  leading  to  elevators,  by  which  they  are  raised 
to  tracks  passing  over  the  coal  bins,  twenty-five  feet  above  the  bottom  of  the  bins, 
which  are  on  a  level  with  the  boiler  floor.  The  coal  is  deposited  in  these  bins  accord- 
ing to  its  quality,  and  from  them  is  loaded  into  small  cars  by  hand  for  transfer  to  the 
fire  room,  and  is  shoveled  from  these  cars  into  the  furnaces. 

In  some  plants  on  the  Continent  the  conveyor  system,  so  much  used  in  America,  has 
been  introduced,  overhead  bunkers,  ash  and  coal  conveyors  being  installed.  The 
motive  power  for  such  machinery  is  electricity  in  all  cases. 

A  large  part  of  the  difference  between  American  and  European  coal- handling  prac- 
tice arises  from  the  different  capacities  of  the  railroad  cars  in  use.  European  cars 
rarely  exceed  twenty  tons  in  capacity,  while  in  America  forty  and  fifty  ton  cars  are  used. 


COAL    STORAGE. 


35 


Comparison  of  Various  Systems.  —  There  are  a  few  of  the  European  coal-handling 
systems  which  are  seldom  found  in  connection  with  American  power  plants.  In  the 
latter  the  coal  is  usually  conveyed  by  the  chain- bucket  system,  and  in  some  instances  by 
belt  conveyors.  This  is  largely  due  to  the  layout  and  construction  of  the  building,  for  in 


FIG.  9.     Longitudinal  Section  of  Boiler  Room,  Williamsburg  Plant,  Brooklyn,  showing  Coal 

and  Ash  Chutes. 

the  European  plants  the  cost  of  land  is  comparatively  small,  the  buildings  are  low  and  the 
coal  bunkers  are  provided  at  the  side,  while  in  America,  where  the  land  is  much  more  ex- 
pensive, the  buildings  are  designed  higher  with  the  bunkers  on  top.  However,  in  connec- 
tion with  recently  constructed  prominent  plants,  as  the  Chelsea  power  plant  of  London, 
the  St.  Denis  plant  of  Paris,*  and  the  power  plant  of  the  Berlin  Subway  and  Elevated 
Road,  belt  and  bucket  conveyors  have  been  employed,  and  without  doubt  in  the  design  of 
future  power  plants  in  Europe  the  overhead  bunker  will  be  much  more  used,  whether 
mechanical  stokers  are  installed,  or  whether  the  old  method  of  hand  firing  be  adhered 
to.  This  will  naturally  cause  a  more  common  use  of  the  conveyor  system.  The  ques- 

*  Power,  February,  1907,  St.  Denis  Power  Plant,  Franz  Koester. 


3<5  STEAM-ELECTRIC    POWER    PLANTS. 

tion  still  remains,  however,  as  to  whether  they  will  convey  the  coal  in  small  quantities 
or  in  greater  bulk,  similar  to  that  at  the  above-mentioned  Vienna  plant,  where  the 
whole  coal  car  is  hoisted  and  dumped  into  the  bunkers.  This  may  be  done  far  more 
readily  in  Europe  than  in  America,  as  there  the  capacity  of  the  cars  is  smaller 
than  those  used  in  America  as  mentioned  above.  Here,  as  well  as  abroad,  the  ten- 
dency toward  conveying  coal  in  large  quantities  is  very  noticeable,  as,  for  instance,  in 
the  Mead-Morrison  coal-handling  system  at  the  Gould  Street  power  house,  Baltimore, 
where  the  coal  is  hoisted  by  a  25  horse-power  steam  engine  up  an  inclined  structure 
in  buckets  of  one-ton  capacity,  and  dumped  into  a  hopper  in  the  tower,  after  it  has 
passed  the  crusher  at  the  base,  operated  by  a  15  horse-power  motor.  From  here  it 
is  dropped  into  cars  operated  by  cables  from  a  10  horse-power  motor.  Another  promi- 
nent system  worthy  of  attention  is  that  at  the  Long  Island  City  Railway  power 
plant,  where  the  coal  is  hoisted  in  grab-buckets  of  one  and  one-half  ton  capacity  to  a 
height  of  about  160  feet,  where  it  is  dumped  into  a  hopper  supplying  the  crusher, 
whence  it  falls  into  the  cars  of  a  cable  road  which  bring  the  coal  to  the  top  of  the 
bunkers  in  the  power  house. 

In  some  plants,  noticeably  that  of  the  Interborough  Rapid  Transit  Co.  of  New 
York  (Subway),  the  coal  handling  is  accomplished  entirely  by  belt  conveyors,  i.e., 
after  the  coal  has  passed  the  crusher  at  the  coaling  tower  it  is  brought  on  belt  con- 
veyors to  the  side  of  the  power  house,  during  which  course  it  is  transferred  to  a  second 
ftelt  conveyor.  It  is  then  raised  by  a  series  of  belt  conveyors  to  the  top  of  the  bunker, 
some  100  feet  above  the  boiler-room  floor,  during  which  journey  it  is  transferred  four 
or  five  times,  as  there  are  two  longitudinal  belt  conveyor  systems  at  the  top  of  the 
bunker.  It  will  be  seen  that  as  each  conveyor  must  be  operated  by  a  separate  motor 
the  liability  of  breakdown  is  materially  increased,  as  of  course  the  failure  of  one  piece 
of  apparatus  means  the  disabling  of  the  entire  system.  In  considering  this  installation 
the  question  immediately  arises  as  to  why  a  vertical  bucket  system  or  a  system  similar 
to  that  at  the  Long  Island  City  plant  was  not  employed.  As  this  belt  conveyor  system 
occupies  the  entire  end  wall  of  the  boiler  room,  the  vertical  system  would  have  saved 
not  only  a  large  amount  of  space,  but  would  also  have  materially  decreased  the  operat- 
ing cost.  Further,  it  is  claimed  by  various  authorities  that  the  entire  coal- handling 
plant  of  the  Long  Island  City  station,  has  been  installed  for  a  small  fraction  of  the 
cost  of  the  above- described  cross-belt  conveyor  system.  Of  course  it  must  be 
admitted  that  the  belt  conveyor  may  have  some  advantages,  especially  on  small 
elevations;  however,  where  side  runs  are  necessary  enormous  space  is  required,  an 
additional  example  of  which  is  found  in  the  new  Boston  Edison  power  station. 
Another  disadvantage  of  the  belt  conveyor  system  is  that  the  belt  cannot  handle 
the  ashes  as  they  come  out  of  the  ash  hopper  of  the  boilers,  if  they  are  red  hot,  as  they 
usually  are.  This  is  a  serious  point  in  view  of  the  common  practice  of  utilizing  the 
same  conveying  apparatus  for  the  handling  of  both  coal  and  ashes. 

Overhead  Bunkers.  —  Overhead  bunkers  are  usually  found  when  the  plant  is  located 
on  expensive  land,  and  such  plants  are  usually  far  above  the  average  in  bunker  capa- 
city, which  ranges  from  five  to  thirty-five  tons  per  lineal  foot. 


COAL    STORAGE.  37 

These  bunkers  are  composed  of  a  steel  framing,  supporting  concrete  or  reinforced 
concrete  flooring,  upon  which  the  coal  lies.  The  bottom  of  the  bunker  slopes  usually 
at  an  angle  of  45°  and  forms  a  series  of  pockets  with  inverted  "V  "-shaped  division 
slopes,  the  coal  chutes  being  attached  to  the  bottom  of  these  pockets.  For  a  double 
row  of  boilers  the  cross-section  of  bunker  is  like  a  "W,"  the  outside  sometimes  being 
carried  up  vertically  to  give  added  depth  when  the  spread  is  carried  to  the  rear  boiler 
columns.  In  some  bunkers  the  floor  slopes  are  made  very  flat,  but  it  is  not  advisable 
to  use  a  slope  less  than  the  angle  of  repose  of  coal,  27°  for  anthracite  and  35°  for  bitumi- 
nous, for  under  ordinary  conditions  such  bunkers  will  be  self -clear  ing.  Convenience 
in  framing,  however,  makes  the  45°  slope  more  desirable,  and  gives  an  added  factor 
to  the  self-clearing  properties  of  the  bunker,  though  under  unfavorable  conditions, 
particularly  after  bunker  fires  have  occurred,  it  may  be  necessary  to  send  men  into 
the  bunker.  The  angle  of  repose  above  mentioned  is  the  natural  slope  taken  by  the 
coal,  and  it  may  be  of  use  in  estimating  the  capacity  of  coal  piles  and  bunkers  when 
the  coal  extends  above  their  top  in  the  pile. 

In  a  few  plants  the  mistake  has  been  made  of  using  such  a  flat-bottomed  bunker 
that  hand  labor  is  necessary  to  shovel  the  coal  over  the  spouts.  Such  bunkers  are 
dangerous  and  frequent  fires  occur  in  them.  Another  type  is  the  suspended  bunker 
of  plate  steel  construction.  Plate  steel  bunkers  usually  run  from  five  to  ten  tons  per 
lineal  foot,  while  masonry  bunkers  run  as  high  as  thirty  to  thirty-five  ton  capacity 
per  running  foot. 

The  use  of  bunkers  is  essential  to  proper  utilization  of  mechanical  stokers,  in  which 
the  feed  hoppers  are  usually  too  high  to  permit  of  the  coal  being  fed  to  them  conven- 
iently by  hand.  In  existing  plants,  when  mechanical  stokers  are  installed,  a  small 
coal  pocket  suspended  from  the  front  boiler  columns  or  the  roof  trusses  is  sometimes 
provided  for  each  boiler,  and  in  other  cases  a  continuous  steel  pocket  is  put  in. 

The  openings  in  the  bottom  of  the  bunkers  may  be  provided  with  cut-off  gates; 
with  steel  plate  construction  the  gate  frames  can  be  secured  to  it,  but  in  concrete  bunkers 
it  is  desirable  to  provide  a  casting  at  the  throat  of  the  pocket,  which  will  resist  the  cut- 
ting action  of  the  moving  coal,  and  furnishes  a  convenient  point  of  attachment  for 
chutes  or  gates. 

In  some  cases  the  chutes  are  bolted  directly  to  the  bunker  casting  with  a  cut-off 
gate  in  it,  while  in  other  cases  a  small  receiving  hopper  loosely  suspended  from  the 
bunker  or  the  steel  frame  of  the  building,  or  a  weighing  hopper,  may  be  placed  at  this 
point.  The  coal  spouts  lead  down  from  these  hoppers.  Sloping  spouts  are  prefer- 
able to  those  in  a  vertical  position,  as  the  coal  has  a  tendency  to  hang  in  vertical  pipes 
and  considerable  ramming  is  often  necessary  to  start  it  running.  In  some  cases  the 
weight  of  coal  in  these  spouts  is  found  by  experiment,  and  an  endeavor  is  made  to 
keep  track  of  coal  consumption  by  counting  the  number  of  times  the  spout  is  filled. 

The  spouts  are  usually  of  cast  iron  of  from  twelve  to  eighteen  inches  in  diameter; 
square  sections  have  been  occasionally  used,  for  the  reason  that  the  coal  does  not 
hang  in  such  spouts  so  readily  as  it  does  in  those  of  circular  section.  When  over-feed 
stokers  are  used  a  spreader-apron  is  required  on  the  lower  part  of  the  spout,  or  else  a 


38  STEAM-ELECTRIC    POWER    PLANTS. 

hinge  is  arranged  so  that  the  coal  can  be  spread  by  swinging  the  spout  laterally.  It  is 
also  necessary  to  hinge  the  spouts  so  that  they  can  be  drawn  back  out  of  the  way  when 
repairs  are  to  be  made  to  the  boiler. 

In  some  plants  a  traveling  hopper  with  chute  is  installed,  having  a  capacity  depend- 
ing upon  the  design  of  the  plant,  in  which  the  coal  is  received  from  the  bunkers  and 
distributed  to  the  boilers  as  required.  This  hopper  can  be  arranged  with  scales  by 
which  accurate  account  can  be  kept  of  the  fuel  consumption. 

Bunker  Fires. — Fires  are  not  infrequent  in  overhead  bunkers,  owing  to  their  being 
exposed  below  to  the  heat  of  the  boiler  room,  and  also  because  coal  is  frequently  stored 
when  wet.  Provision  has  been  made  in  a  number  of  plants  by  overhead  water  lines  for 
fighting  such  fires,  but  experience  proves  that  water  is  a  poor  method  of  combating  them, 
as  they  are  usually  in  the  lower  part  of  the  bunker,  and  water  reaches  everything  but  the 
fire.  Steam  can  be  injected  into  the  bottom  of  the  bunkers  through  the  gates,  or,  as 
fires  may  occur  with  considerable  frequency,  it  might  be  desirable  to  install  a  special 
pipe  system  to  smother  same.  The  best  method,  however,  to  control  a  bunker  fire 
in  the  shortest  possible  time  is  to  empty  the  particular  bunker  through  the  spouts  and 
attack  the  fire  at  the  boiler-room  floor.  Where  the  coal-handling  facilities  are  such 
as  to  allow  of  distributing  the  coal  throughout  a  number  of  boilers,  it  might  be  well 
immediately  to  convey  the  coal  which  is  on  fire  to  the  boilers  and  have  it  burned  up 
as  rapidly  as  possible.  While  this  method  may  seem  radical  and  may  mean  a  con- 
siderable loss  in  coal  it  is,  in  the  writer's  opinion,  the  best  method  of  procedure,  as  the 
loss  entailed  would  be  but  a  very  small  item  compared  to  what  it  would  be  were  the 
fire  allowed  to  gain  a  headway  and  spread  over  the  entire  supply. 


CONDENSER    WATER    SUPPLY. 

Inlet  and  Outlet  Tunnels.  —  The  large  modern  power  plant  is  always  equipped 
with  condensing  apparatus,  owing  to  the  greater  economy  secured  by  using  steam 
with  greater  expansion.  The  amount  of  circulating  water  required  to  condense  a  given 
quantity  of  steam  varies  according  to  the  initial  temperature  of  the  circulating  water, 
and  its  permissible  rise  in  temperature.  For  moderate  vacua  the  weight  of  condensing 
water  is  from  20  to  30  times  that  of  the  steam  to  be  condensed,  whereas  for  high 
vacuum  work  with  surface-condensers  it  runs  up  to  60  or  80  times  the  weight  of  the 
steam. 

Owing  to  the  great  quantity  of  water  required  for  condensing,  an  independent 
supply  is  necessary  for  this  purpose,  since  it  would  not  be  practicable  to  draw  such  a 
large  amount  of  water  from  the  city  mains.  In  plants  located  where  salt  water  is 
available  it  is  used  in  the  condensers,  and  where  located  in  the  interior,  on  fresh  waters, 
the  unfiltered  river  water  is  used.  This  water  is  drawn  in  through  an  intake  which 
is  generally  constructed  of  concrete,  or  reinforced  concrete,  but  occasionally  of  iron 
pipes,  and  in  some  rare  cases  wooden  flumes  of  considerable  length  have  been  erected. 


CONDENSER    WATER    SUPPLY.  39 

Screen  Chamber.  —  As  this  water  is  always  liable  to  contain  floating  debris  of 
various  kinds,  or  ice,  a  rack  should  be  provided  across  the  mouth  of  the  intake. 
This  is  preferably  constructed  of  wide  oak  slats,  or  flat  iron  bars  placed  side  by  side. 
The  opening  between  the  bars  should  not  exceed  one  inch,  and  sufficient  area  must  be 
provided  to  permit  a  maximum  flow  with  a  moderate  velocity,  in  order  that  the  surface 
of  the  rack  can  be  raked  clean  with  the  least  trouble,  and  also  to  provide  for  the  block- 
ing up  of  considerable  area.  Inside  of  this  rack  an  additional  screen  with  fine  meshes 
should  be  placed.  This  latter  is  preferably  double  and  in  sections,  so  that  any  part  of 
the  sections  can  be  removed  and  cleaned  while  the  others  are  in  operation.  This  screen 
is  usually  a  heavy  timber  frame,  across  which  copper  wires  are  strung  at  right  angles 
to  each  other,  or  in  some  cases  galvanized  iron  wire  has  been  used.  This  latter 
material,  however,  is  liable  to  deteriorate  very  quickly,  owing  to  the  galvanized  sur- 
face being  cracked  in  bending  the  wires. 

Shut-off  Gates.  —  It  is  advisable  to  provide  shut-off  gates,  either  to  be  inserted  in  the 
grooves  over  the  wire  screens  or  immediately  back  of  the  outer  rack.  These  gates  are 
necessary  to  shut  off  the  water  when  the  intake  tunnel  must  be  cleaned  out.  When  these 
shut-off  gates  are  of  considerable  size  it  is  necessary  to  provide  a  by-pass  in  them  in  order 
that  the  water  pressure  may  be  equalized  on  both  sides  of  the  gate,  thus  reducing,  to  a 
large  extent,  the  power  required  to  raise  them.  This  intake  head  should  be  compactly 
arranged  in  order  to  secure  economy  of  construction,  and  either  a  light  structure  should 
be  erected  over  it  on  which  chain  block  hoists  and  trolley  can  be  installed  to  handle 
the  gates  and  screens,  or  if  power-operated  machinery  is  put  in  for  this  purpose  it  is 
desirable  to  erect  a  regular  gatehouse. 

Area  of  Tunnels  and  Screens.  — The  pump  suctions  should  be  laid  from  recesses 
or  pits  in  the  side  of  the  intake,  out  of  the  direct  current,  because  the  large  pipes 
required  for  this  purpose  would  block  up  the  flow  of  water. 

The  sectional  area  of  the  tunnel  should  be  proportioned  to  supply  the  maximum 
requirements  of  the  plant  at  a  velocity  not  to  exceed  5  to  6  feet  per  second,  depending 
somewhat  on  the  construction  of  the  conduit  tunnel.  The  intake  rack  should  be  pro- 
vided for  a  velocity  of  about  2^  feet  per  second,  or  about  50  per  cent  excess  area  over 
that  of  the  tunnel.  In  some  cases  higher  velocities  than  above  mentioned  have  been 
used,  but  such  a  practice  is  not  advisable,  as  it  reduces  the  efficiency  of  the  pumping 
machinery,  or,  in  other  words,  increases  the  amount  of  power  required  to  handle  the 
water. 

Arrangement  of  Tunnels.  —  The  intake  tunnel  should  be  located  at  a  sufficient 
depth  to  secure  water  at  the  lowest  stage  of  the  tide,  or  the  lowest  water  level  of  the 
river.  Where  possible  the  outlet  tunnel  should  be  on  the  same  level,  in  order  to  take 
advantage  of  the  siphon  action  which  will  be  set  up  when  the  current  through  the  con- 
denser has  been  established.  With  this  construction  the  circulating  pump  is  only  re- 
quired to  overcome  the  friction  of  the  water  through  the  condenser  and  pipes,  and  the 


40  STEAM-ELECTRIC    POWER    PLANTS. 

power  consumption  is  reduced  to  a  minimum.  Owing  to  local  conditions  it  is  in  many 
cases  impossible  to  adopt  this  design,  and  for  such  cases  the  outlet  tunnel  should  be  above 
the  intake,  in  order  to  reduce  the  amount  of  excavation  required  for  the  two  tunnels,  the 
inlet  and  discharge  pits  from  the  condenser  being  brought  down  on  the  sides  of  the  con- 
duits. The  mouth  of  the  outlet  tunnel  should  lie  at  some  distance  from  the  intake, 
preferably  in  the  direction  in  which  the  current  of  the  stream  flows,  and  the  farther 
they  are  separated  the  better,  in  order  that  the  outlet  water  may  not  be  drawn 
back  to  the  intake,  as  this  might  reduce  the  efficiency  of  the  condensers  considerably, 

Scarcity  of  Condenser  Water. —  In  many  localities  it  is  difficult  to  secure  a  sufficient 
supply  of  water  for  condensing  purposes,  and  for  such  plants  it  is  necessary  to  use 
the  circulating  water  over  and  over  again.  There  are  several  methods  in  service  for 
cooling  the  water  sufficiently,  such  as  cooling  towers  and  ponds.  This  subject,  how- 
ever, will  be  treated  more  fully  under  this  specific  heading. 


CHAPTER  III. 
EXCAVATION  AND  FOUNDATION. 

Selection  of  Site.  —  Obviously  one  of  the  first  things  to  be  considered  in  the  selec- 
tion of  a  suitable  site  is  the  character  of  the  foundations  required,  and  where  accurate 
and  reliable  information  cannot  be  obtained  in  other  ways,  some  preliminary  ex- 
ploration is  advisable,  before  the  purchase  of  the  property  is  concluded.  In  order 
to  secure  economy,  and  at  the  same  time  avoid  all  danger  of  insufficient  foundations, 
it  is  a  good  plan  to  test  the  bearing  value  of  the  soil.  This  can  be  conveniently 
done  by  sinking  test  pits  within  the  area  of  the  proposed  excavation,  and  applying 
a  test  load,  or  the  test  load  can  be  omitted  when  soil  of  a  well-known  character  is 
found. 

Test  Holes.  —  In  alluvial  soil  or  made  land  a  thorough  exploration  should  be  made 
by  borings  carried  deep  enough  to  give  an  accurate  knowledge  of  the  underlying  strata. 
When  rock  is  met  with  it  should  be  pierced  to  a  sufficient  depth  to  make  certain  that  it 
is  not  an  isolated  boulder.  The  holes  should  be  put  down  from  twenty-five  to  fifty  feet 
apart  and  should  be  located  so  that  an  intelligible  plot  can  be  made.  When  the  mag- 
nitude of  the  project  does  not  warrant  the  use  of  well  or  core  drilling  machines,  test 
holes  can  be  put  down  by  driving  iron  pipe ;  a  small  pipe  and  a  large  one  can  be  used, 
the  large  one  being  used  as  a  casing  to  prevent  the  hole  caving  in  and  the  smaller 
pipe  being  driven  inside  of  it.  A  core  can  be  secured  by  leaving  the  lower  end  of  the 
smaller  pipe  open  and  working  without  water,  but  an  easier  method  is  to  force  a 
stream  of  water  down  the  smaller  pipe,  which  returning  to  the  surface  by  the  larger 
pipe  brings  up  specimens  of  the  soil.  With  a  device  of  this  kind  holes  can  be  put 
down  fifty  feet  more  or  less,  dependent  upon  the  character  of  the  ground. 

Character  of  Soil.  —  When  rock  is  met  within  a  moderate  depth,  the  foundations 
should  be  carried  down  to  it,  the  surface  of  the  rock  under  the  piers  and  walls  should 
be  leveled  off  to  give  a  good  bearing,  all  loose  and  rotten  stone  being  cleaned  off 
until  a  solid  material  is  reached.  The  bearing  value  of  rock  varies  within  wide  limits, 
according  to  its  quality,  from  20  to  200  tons  per  square  foot,  the  allowable  value  being 
one-tenth  of  its  crushing  strength. 

A  clean  sand  makes  an  ideal  foundation,  having  a  good  bearing  value  and  being 
easy  to  excavate,  in  addition  it  can  be  utilized  in  the  mortar  and  concrete,  with  con- 
siderable saving  in  expense.  Gravel,  except  of  the  cemented  kind,  possesses  similar 

41 


42  STEAM-ELECTRIC    POWER    PLANTS. 

advantages.  Quicksand,  either  wet  or  dry,  when  in  thin  layers  should  be  entirely 
removed;  where  the  bed  is  underlaid  by  a  firm  strata,  and  removal  is  impracticable, 
it  can  be  confined  by  means  of  a  concrete  cofferdam,  and  the  foundation  can  then  be 
floated  on  it,  the  footing  or  mat  covering  the  entire  area  within  the  dam. 

In  soft  alluvial  soil  or  made  land,  piling  is  necessary  for  heavy  foundations.  Piling 
is  used  in  two  ways :  piles  are  driven  to  rock  or  to  a  solid  stratum  below,  in  which  case 
they  act  as  columns  supporting  the  foundation ;  or  they  are  driven  down  in  soft  soil 
to  compact  it,  in  which  case  their  bearing  power  is  dependent  entirely  on  the  friction 
between  the  piles  and  the  soil.  Wooden  piles  must  be  cut  off  below  the  level  of  the 
permanent  ground  water  line  in  order  to  preserve  them  from  decay;  in  some  localities 
there  is  considerable  difficulty  in  locating  the  ground  water  line,  which  is  liable  to  sink 
or  rise  several  feet  according  to  whether  the  season  is  wet  or  dry.  In  early  practice 
a  wooden  platform  wras  laid,  built  up  of  caps,  drift  bolted  to  the  tops  of  the  piles,  on 
which  the  heavy  flooring  of  squared  timbers  was  laid;  this  was  necessary  in  the  days 
when  foundations  were  built  up  of  dimension  stone  and  brick.  The  modern  practice 
is  to  use  a  mat  of  concrete,  in  which  the  tops  of  the  piles  arc  encased  six  inches  to  a 
foot;  when  the  character  of  the  soil  is  such  that  it  is  difficult  to  deposit  concrete  directly 
on  it,  it  is  customary  to  excavate  between  the  piles  to  a  depth  of  two  to  four  feet  and 
fill  in  with  sand  or  gravel  in  thin  layers  well  rammed. 

As  a  general  rule  the  firmness  of  the  soil  increases  with  depth,  but  there  are  excep- 
tions; in  Chicago  there  is  a  firm  upper  layer  of  soil  from  ten  to  twenty  feet  in  thick- 
ness underlaid  by  a  soft  clay  stratum  about  seventy  feet  in  thickness,  beneath  which 
is  a  thick  stratum  of  very  firm  clay;  this  same  condition  prevails  in  many  localities 
near  lakes  or  rivers,  and  also  in  Holland.  The  early  practice  in  building  foundations 
on  such  soil  was  to  float  them  on  a  sort  of  a  raft  or  mat  covering  the  entire  area;  in  some 
cases  piles  were  driven  before  this  mat  was  put  in.  In  building  foundations  for  some 
plants  a  number  of  isolated  piers  have  been  used  for  supporting  the  buildings 
and  machinery,  the  principal  disadvantage  of  such  construction  being  the  impos- 
sibility of  insuring  equal  settlement  of  all  the  different  piers. 

Clay  varies  greatly  in  consistency,  ranging  from  very  nearly  a  fluid  to  a  hard  shale; 
this  latter  on  exposure  absorbing  water  from  the  atmosphere  and  disintegrating.  Clay 
varies  greatly  according  to  the  opportunity  it  has  of  absorbing  or  losing  water,  and  this 
property  makes  it  troublesome.  It  is  desirable  to  arrange  so  that  it  will  be  thoroughly 
drained,  but  this  may  cause  trouble  with  surrounding  structures,  numerous  instances 
of  which  have  occurred  in  Chicago.  Sand  or  stone  can  be  spread  on  clay  over  the 
area  to  be  covered  by  the  foundation,  being  well  rammed  down;  the  stones  used  for 
this  purpose  should  be  small  enough  to  permit  their  being  handled  by  one  man. 

Concrete  Mat  Construction.  —  Since  power  houses  are  usually  built  on  the  water 
front,  it  frequently  happens  that  alluvial  soil  or  made  ground  is  met  with,  in  which 
cases  piling  must  be  used  unless  a  firm  underlying  stratum  is  found  sufficiently  close 
to  the  surface  to  justify  the  carrying  of  the  foundations  down  to  it.  In  soil  of  this 
character  it  is  sometimes  attempted  to  economize  by  the  use  of  piles  and  isolated 


EXCAVATION    AND    FOUNDATION.  43 

piers,  but  the  result  is  not  satisfactory.  In  such  places  the  purpose  of  the  foundation 
is  not  to  prevent  settlement,  but  to  insure  that  such  settlement  as  occurs  will  be  equal 
over  the  entire  area;  this  can  be  best  insured  by  driving  piles  over  the  entire  area  and 
placing  a  heavy  mat  of  concrete  over  them,  tying  the  heads  of  the  piles  together 
firmly.  The  mass  of  this  mat  and  the  foundations  should  be  sufficient  to  take  up 
all  the  vibration  due  to  the  machinery,  which  is  rarely  in  thorough  running  balance. 
In  a  case  in  Holland  the  entire  structure  developed  a  tendency  to  slide  bodily  in  one 
direction,  owing  to  the  unbalanced  moment  of  the  engines,  which  happened  to  be 
in  synchronism  with  each  other.  The  trouble  was  cured  by  running  some  of 
the  machines  in  the  opposite  direction,  which  caused  their  moments  to  oppose  each 
other. 

A  prominent  example  of  the  mat  construction  for  foundations  is  the  Long  Island 
City  power  plant  of  the  Pennsylvania,  New  York  and  Long  Island  Railroad  Co.,  which 
has  an  ultimate  capacity  of  fourteen  5,500  K.W.  and  two  2,500  K.W.  Westinghouse- 
Parsons  turbo-generators.  The  plant  is  located  on  a  plot  of  ground  200  X  500  feet, 
a  length  of  265  feet  being  at  present  all  that  is  occupied.  Wooden  piles  25  to  30  feet 
in  length  were  driven  over  the  entire  area,  as  seen  in  accompanying  illustration  Fig.  i, 
their  center  distances  varying  from  two  feet  to  three  feet  four  inches,  being  closest 
together  under  the  stacks  and  at  other  points  where  heavy  concentrated  loads  occurred. 
About  9,500  piles  were  driven,  and  they  were  cut  off  at  a  uniform  height.  Over  the 
piles  a  monolithic  mat  of  concrete  is  placed,  in  the  lower  side  of  which  the  heads  of  the 
piles  are  embedded.  This  mat  is  six  feet  thick  and  the  concrete  used  is  a  i  :  2\  •  5  mix- 
ture of  Portland  cement,  sand  and  broken  stone.  This  concrete  was  placed  in  winter, 
and  to  avoid  all  trouble  from  freezing  the  precaution  was  taken  thoroughly  to  drain 
it  by  means  of  cross  and  longitudinal  drains,  of  10  and  12  inch  vitrified  tile  pipe.  The 
entire  structure  rests  on  this  mat.  Cross  grillages  of  1 2-inch  I  beams  are  used  to  dis- 
tribute the  column  loads,  the  beams  being  embedded  in  concrete;  the  columns  are 
bolted  to  the  upper  layer  of  the  grillage. 

Concrete  Piles.  —  The  use  of  concrete  for  various  purposes  is  increasing,  and  in 
addition  to  its  use  for  foundations  of  a  massive  character  it  is  also  employed  for 
walls,  floors  and  piles,  being  used  both  plain  and  reinforced  with  steel.  Two  methods 
are  employed  for  concrete  piles;  in  one  the  piles  are  molded  and  then  driven,  in 
the  other  a  mold  is  driven  with  a  removable  core  and  the  concrete  placed  after  the 
removal  of  the  core.  The  concrete  pile  is  comparatively  new,  and  several  different 
forms  are  widely  advertised;  for  many  reasons  they  are  preferable  to  timber  piles; 
they  cannot  decay,  and  for  this  reason  they  can  be  brought  up  as  high  as  desired  and 
more  economical  foundations  secured  owing  to  the  fact  that  the  ground  water  line  does 
not,  with  concrete  piles,  signify  the  point  where  the  footing  for  the  piers  must  be  laid. 
This  may  mean  a  great  saving  in  the  line  of  excavation  and  foundations.  As  the 
bearing  power  of  concrete  is  much  higher  than  that  of  wood,  heavier  loads  can  be 
placed  on  a  pile,  while  at  the  same  time  there  is  no  limit  on  the  size  or  diameter  at  the 
butt  as  is  the  case  with  wood;  wood  piles  rarely  run  over  12  to  14  inches  at  the  butt; 


44 


STEAM-ELECTRIC    POWER    PLANTS. 


for  ordinary  work,  since  large  timbers  are  very  expensive,  concrete  piles,  as  large  as 
desired,  within  limits,  can  be  used.     For  this  reason  fewer  concrete  piles  will  be 


FIG.  i.     Piles  cut  off  ready  for  Concrete  Cap,  Long  Island  City  Plant. 

required  for  the  support  of  a  given  load,  and  they  are  in  effect  downward  projections 
of  the  monolithic  mass  of  the  foundations. 

Test  of  Piles.  —  The  difference  in  bearing  power  between  a  conical  and  a  cylin- 
drical pile  was  shown  by  an  experiment  tried  on  some  work  at  the  United  States  Naval 
Academy  at  Annapolis,  Md.  A  Raymond  pile  core,  tapering  from  six  inches  at  the 
point  to  twenty  inches  at  the  butt,  was  driven  19  feet,  until  the  penetration  under  two 
blows  from  a  2,ioo-pound  hammer  falling  twenty  feet  was  seven-eighths  of  an  inch. 
A  wooden  pile  9 \  inches  at  the  point  and  1 1  inches  at  the  butt,  and  of  the  same  length, 
19  feet,  as  the  conical  pile,  had  a  penetration  of  5  A  inches  under  two  blows  of  the 
same  hammer  falling  20  feet.  A  ly^-foot  test  pile  having  the  same  dimensions  as  the 
concrete  pile  above  mentioned,  and  having  a  penetration  of  i  inch  under  twenty  blows 
of  a  steam  hammer,  was  loaded  with  41  tons.  Levels  were  taken  during  the  loading 
and  at  intervals  for  one  month.  At  the  end  of  the  month  the  total  settlement  was 
0.007  f°°t  or  $z  inch. 

Bearing  Power  of  Soil.  —  The  size  of  the  foundation  necessary  for  supporting  the 
load  to  be  carried  is  of  the  first  consideration.  In  the  matter  of  the  machinery  care 
should  be  taken  to  include  the  entire  weight,  including  the  water  in  heaters,  con- 


EXCAVATION    AND    FOUNDATION. 


45 


.Si'a'ewalk  leYfl 


m*&&&j1!:'3 
W*4>&$$& 

i£tf*:tf#?£^ 

£^>V-°.'-->.;:..:- 
'*'. .'•&'• '•.-.•&:  -  •>/.»'•':'.  c< 
'i-.-V-.,:?:  r..OX;-...    A! 


^0;:;^:^;."- 


g^^% 


42%M£3$&£ 

:^?^-1?:^^^V 


S^^t^g 

'•^••^•^••v^ 

^ip^* 

•••o:-'i.-.-x-:":0--"-'-:-j:-. 


fla<.  //go r  Z*r«/i 


• 


Reinforced  Concrete 


Wood  Piling 


FIG.    2.     Comparison   between    Foundation   employing  Wooden   Piling  and  Foundation 

with  Concrete  Piles. 


46 


STEAM-ELECTRIC    POWER    PLANTS. 


densers,  etc.     For  the  safe  bearing  power  of  soils  the  values  in  the  following  table  as 
given  in  Baker's  Treatise  on  Masonry  Construction  are  submitted : 

TABLE   III—  SAFE   BEARING    POWER  OF  SOILS. 


KIND  OF  MATERIAL. 

SAFE  REARING 
POWER  IN  TONS 
PER  Sr>.  FOOT. 

Min. 

Max. 

Rock  —  the  hardest  —  in  thick  layers,  in  native  bed  

200 
25 
T5 
5 
4 

2 

8 
4 

2 

o-S 

3° 

20 
IO 

6 
4 

IO 

6 

4 
i 

Rock,  equal  to  best  ashlar  masonry    

Rock   equal  to  best  brick  masonry     

Rock,  equal  to  poor  brick  masonry    

Clay,  in  thick  beds,  always  drv   

Clay   in  thick  beds,  moderatelv  drv            

Gravel  and  coarse  sand,  well  cemented     

Sand,  compact  and  well  cemented  

Sand,  clean,  dry      

Quicksand,  alluvial  soils,  etc  

Weight  of  Masonry.  —  For  the  total  bearing  stress  of  a  foundation  on  the  soil 
the  weight  of  the  foundation  itself  must  be  included.  For  use  in  this  connection, 
Table  IV,  taken  from  the  same  authority,  gives  the  weights  of  various  types  of 
masonry : 

TABLE   IV  — WEIGHT    OF   MASONRY. 


KIND  OF  MASONRY. 

WEIGHT 
IN  LBS. 
PER  Cu.  FT. 

M5 
125 
100 

140 
1  60 

155 
148 
142 

136 

116 

100 

Brickwork   soft  brick    thick  joints                              

Limestone   ashlar    12"  to  20"  courses  and  §"  to  \"  joints      

Size  of  Foundation.  —  The  sizes  of  foundations  are  ordinarily  given  by  manu- 
facturers, either  in  catalogues  or  blue  prints,  which  are  easily  procured.  In  many 
instances,  however,  the  low  bearing  power  of  soils  necessitates  the  use  of  foundations 
larger  than  those  so  given.  In  such  cases  sizes  must  be  figured  for  the  hearing  power 
of  the  soil  in  question,  samples  of  which  have  been  previously  obtained  on  the  ground. 
In  cases  where  detailed  drawings  of  foundations  are  not  furnished  by  manufacturers, 
care  should  be  exercised  to  have  the  foundations  for  reciprocating  machines  of  ample 
mass  to  take  care  of  shocks  and  vibrations  due  to  the  motion  of  the  parts  of  the  machine. 


EXCAVATION  AND  FOUNDATION.  47 

Location  of  Foundation.  —  In  locating  a  foundation  every  precaution  should  be 
taken  to  see  that  the  center  lines  are  properly  established,  and  that  the  dimensions 
are  properly  laid  out,  inasmuch  as  a  foundation  once  in  place  is  very  hard  to  remove. 
This  may  also  be  said  in  regard  to  the  location  of  the  anchor  bolts.  Substantial 
templets  should  be  constructed  so  that  the  anchor  bolts  will  remain  in  their  proper 
position  while  the  concrete  is  being  filled  in  around  them.  Anchor  bolts  may  be  either 
embedded  directly  in  the  concrete,  or  where  very  long  anchor  bolts  are  used  iron  pipes 
may  be  placed  around  them,  in  order  to  allow  space  for  adjusting  the  bolts  to  the 
machine  bed-plates.  Where  pipes  are  not  used,  wooden  boxes  may  take  their  place. 
These  wooden  forms  are  generally  removed  at  the  completion  of  the  foundation,  but 
the  pipes  remain.  In  cases  where  permanent  pipes  are  embedded  in  the  concrete 
and  anchor  bolts  are  to  be  inserted  at  the  time  of  the  erection  of  the  engine,  such 
pipes  should  be  supplied  with  wooden  plugs  so  that  no  foreign  matter  may  fall  in 
upon  the  anchor  plates  and  prevent  the  possibility  of  readily  entering  the  bolts. 

Concrete  Forms.  —  In  the  construction  of  forms  for  smaller  foundations  these  should 
be  so  made  that  they  may  be  easily  taken  apart  and  used  again.  The  thickness  of  the 
planking  and  timbers  used  for  forms  will  depend  on  the  size  and  height  of  the  foundation. 
A  foundation  25  feet  high,  as  has  been  used  for  large  units  in  some  of  the  New  York 
power  plants,  requires  heavier  material  than  is  necessary  for  foundations  for  smaller 
units.  Where  the  exterior  finish  of  the  foundation  is  required  to  be  smooth  or  exposed 
to  view,  the  planking  material  should  be  surfaced  and  edged  so  as  to  make  a  smooth, 
tight-fitting  form.  In  such  cases  gravel  or  stone  should  be  well  worked  back  from  the 
form,  so  as  to  leave  a  cement  face.  The  concrete  used  for  bedding  foundations  is 
usually  i :  2\  :  5,  or  in  cases  where  heavier  foundations  have  been  employed  the  mixture 
is  i  :  3  :  6.  The  mixing  plant  should  be  located  as  near  the  foundation  as  possible  in 
order  to  facilitate  the  handling  of  material.  In  prominent  power  plants  a  mechanical 
mixer  has  been  installed.  Special  sheds  have  been  erected  to  store  the  cement,  while 
stone  and  gravel  are  stored  at  the  side  of  the  mixers. 

Concrete  Mixture.  —  The  sand  used  for  concrete  should  be  clean  and  sharp. 
The  cement  should  be  of  the  best  quality,  freshly  ground  Portland.  The  broken 
stone  should  be  thoroughly  clear  of  mud,  dust  and  dirt,  and  should  be  not  of  larger 
size  than  will  pass  through  a  two-inch  ring  in  any  direction.  Concrete  for  foundations 
should  be  mixed  rather  wet  and  well  rammed  in  place  until  a  film  of  water  stands  on 
the  surface.  The  concrete  should  be  quickly  laid  in  thin  layers  not  to  exceed  nine 
inches  in  thickness,  and  each  layer  well  rammed  before  the  next  succeeding  layer  is 
applied.  In  the  construction  of  the  various  piers  and  parts  of  a  foundation  each 
should  be  carried  to  completion  without  interruption  after  the  work  is  once  begun,  so 
as  to  secure  a  homogeneous  and  monolithic  mass.  The  forms  should  not  be  removed 
until  the  concrete  is  set.  All  foundations  should  be  allowed  to  set  at  least  several 
days,  dependent  on  the  size  of  the  foundation,  before  any  machinery  is  placed.  In 
dumping  concrete  the  fall  should  not  be  more  than  8  to  10  feet,  for  the  reason  that, 


OF    THE 

UNIVERSITY 

OF 


48 


STEAM-ELECTRIC    POWER    PLANTS. 


at   such    heights,  the   gravel    will   separate  in  its    fall    from  the  cement,  and  water- 
pockets  will  form  around  the  gravel  tending  to  destroy  the  bond. 

Grouting.  —  Allowance  should  be  made  on  top  of  foundations,  varying  from  one 
half  to  one  inch  between  the  foundation  and  the  bottom  of  the  bed-plate,  for  grout- 
ing.   After  the  bed-plates  have  been  adjusted  in  place  and  securely  anchored,  all  of  the 
space  left  between  the  foundation  and  bed-plate,  and  around  the  anchor  bolts,  is  filled 
with  a  rich,  thin  cement  mortar. 

Waterproofing.  —  Usually  the  building  foundation  is  made  of  monolithic  con- 
crete; where,  however,  brick  is  preferred,  first-class  material  only  should  be  used. 
The  brick  should  be  of  hard  burned  clay,  the  mortar,  Portland  cement.  Wher- 
ever the  building  foundations  are  located,  be  they  of  concrete  or  brick,  and  providing 
the  soil  be  damp,  provision  should  be  made  to  waterproof  same. 


BUILDING. 

Material.  —  In  power  plants  a  prime  necessity  is  a  fireproof  building,  guaranteeing 
continuity  of  service.  This  can  best  be  secured  by  a  structure  entirely  of  brick,  steel  or 
concrete.  The  following  materials  are  available :  granite,  concrete  blocks,  terra  cotta, 
reinforced  concrete,  common  brick  and  corrugated  iron.  The  advantages  of  any 
particular  method  of  construction  must  depend  upon  the  class  of  labor  available.  In 
many  countries  skilled  labor  is  easily  obtainable.  In  others  everything  must  be  brought 
to  the  building.  In  the  latter  case  it  is  advisable  to  use  materials  which  can  be  handled 
by  casual  labor,  such  as  corrugated  iron  siding  or  reinforced  concrete,  which  can  be 
molded  to  suit  the  structure.  A  skilled  foreman,  however,  is  necessary. 


.  r 


FIG.  i.     Delaware  Ave.  Plant,  Philadelphia. 

Floors.  —  In  the  boiler  room  a  concrete  floor  is  typical  of  the  best  construction. 
In  many  plants  brick  pavement  has  been  successfully  used  in  this  portion  of  the  building. 


BUILDING. 


49 


In  designing  concrete  floors,  both  for  boiler  and  generating  room,  it  is  desirable  to 
provide  drainage  slopes  with  floor  drains  at  suitable  points  so  that  wash-water,  drips, 
leakage,  etc.,  will  not  form  puddles.  All  corners  where  this  floor  abuts  at  the  founda- 
tions or  walls  should  be  rounded  and  no  sharp  corners  should  be  permitted  anywhere 
in  the  plant.  This  serves  a  two-fold  purpose :  re-entrant  corners  are  rounded  for  sani- 
tary reasons,  while  projecting  corners  are  rounded  to  avoid  chipping  off  by  accident. 

In  large  plants  the  flooring  is  often  kept  back  from  around  the  generators,  which 
extend  down  into  the  basement  to  allow  room  for  the  removal  of  the  fields  or  armature. 
In  American  plants  sometimes  a  removable  wooden  floor  is  put  in  for  such  openings. 
In  Europe,  particularly  on  the  Continent,  the  practice  is  to  run  the  concrete  floor  close 
up  to  the  generator  frames,  leaving  a  small  amount  of  clearance  to  avoid  danger  of 
short  circuits.  This  flooring  is  arranged  so  that  it  can  be  broken  out  should  it  be  neces- 


FIG.  2.     Fisk  Street  Plant,  Chicago. 

sary  to  remove  the  entire  machine,  so  very  rare  an  occurrence,  however,  that  it  is  not 
necessary  to  spoil  the  appearance  of  the  plant  to  cover  such  an  emergency. 

In  modern  practice  reinforced  concrete  has  been  frequently  employed  with  great 
success.  These  concrete  floors,  usually  of  five  inches  thickness,  contain  a  layer  of  wire 
netting  or  iron  rods,  and  are  molded  directly  on  the  floor  framing  without  arching. 
This  construction  has  many  advantages,  the  principal  difficulty,  however,  lies  in  the 
fact  that  holes  cannot  be  broken  in  the  flooring  without  cutting  the  reinforcement. 

Some  authorities  claim  that  brick  or  cement  flooring  is  undesirable  in  rooms  con- 
taining machinery,  on  account  of  the  grit  produced  by  wear  being  stirred  up  by  walk- 
ing or  sweeping,  and  recommend  wooden  flooring.  Wooden  flooring  should  not  be 
used  for  the  reason  that  around  machinery  there  is  more  or  less  dripping  of  oil  which 
soaks  into  the  floor,  and  very  shortly  gets  it  into  a  very  inflammable  condition.  In 
fact,  the  whole  trouble  with  some  power  plant  fires  has  been  due  to  an  insignificant 
blaze  in  the  wooden  flooring  causing  thousands  of  dollars  worth  of  damage  to  the 


STEAM-ELECTRIC    POWER    PLANTS. 


o 
U 


PH 

W) 

C 


u 


o 

"rt 

•(-> 
C 

5 


I 


BUILDING.  5 1 

apparatus.  In  an  electric  power  station  it  is  almost  impossible  to  use  water  in  case  of 
fire  on  account  of  the  danger  of  short  circuits,  and  sand  or  earth  must  be  spread  on  the 
blaze. 

The  floor  arches,  whether  all  brick  or  concrete,  should  be  so  designed  that  their 
crown  is  below  the  level  of  the  tie  rods  in  the  floor  system.  This  question  has  been 
treated  in  the  chapter  on  steel  structure. 

In  many  plants  bluestone  bearers  are  set  in  foundations,  and  in  the  walls  of  the 
building  where  the  floor  beams  bear.  This  is  an  unnecessary  refinement,  since  it  is 
perfectly  practicable  to  use  a  heavy  steel  plate  for  this  purpose,  which  can  be  grouted 
in  position  with  much  less  trouble  than  is  required  to  set  the  bluestone  accurately. 
Cast-iron  or  built-up  lintels  should  also  be  so  proportioned  that  the  use  of  stone  bear- 
ing plates  is  unnecessary,  for  steel  properly  grouted  is  much  better. 


FIG.  4.     Structure  of  Waterside  Plant  No.  2,  New  York  (Electrical  Worlif). 

Pipe  Trenches.  —  All  piping  should  be  run  in  an  inconspicuous  manner,  preferably 
in  trenches  under  the  floor,  with  the  exception  of  live  steam  piping,  or  if  there  is  a  base- 


52  STEAM-ELECTRIC    POWER    PLANTS. 

ment  in  the  plant,  as  is  the  case  with  reciprocating  engine  stations  and  horizontal 
turbine  plants,  the  piping,  as  far  as  possible,  should  be  kept  in  the  basement.  Where 
it  is  necessary  to  bring  pipes  through  the  floor,  they  should  be  surrounded  by  cast-iron 
thimbles,  which  should  extend  at  least  one  inch  above  the  floor  to  prevent  wash- 
water  damaging  the  pipe  covering.  In  some  instances,  however,  as  a  matter  of  appear- 
ance, these  thimbles  are  made  flush  with  the  floor  construction.  An  endeavor  should 
be  made  to  locate  all  these  floor  openings  before  the  forms  for  the  floors  are  built.  In 
case  these  floors  have  to  be  put  in  before  the  piping,  it  is  advisable  to  build  in  tempo- 
rary wooden  forms  somewhat  larger  than  the  thimble  proposed  to  be  used,  so  that  the 
thimble  can  be  centered  on  the  piping  after  it  is  installed.  The  thimbles  used  for 
this  purpose  should  be  of  sufficient  size  to  permit  the  pipe  flanges  to  pass  through 
them  with  ease. 

Switchboard  Gallery.  —  In  the  switchboard  gallery  concrete  floors  must  be  designed 
so  as  to  give  suitable  room  for  all  ducts  and  passages  necessary  for  the  wiring.  In 
some  plants  part  of  the  flooring  is  made  out  of  slate  or  soapstone  slabs,  which  can 
be  removed  should  the  necessity  arise.  The  reason  for  employing  these  materials 
is  that  these  stones  contain  very  few  metallic  elements  and  are,  in  effect,  first-class 
insulators. 

Walls.  —  The  engine  room  should  be  separated  from  the  boiler  room  by  a  fire  wall, 
with  as  few  openings  as  practicable,  and  these  openings  should  be  closed  by  fireproof 
doors.  This  wall  is,  in  some  countries,  required  by  the  fire  underwriters  to  project  several 
feet  above  the  roof,  and  wherever  pipe  openings  are  necessary  in  it  cast-iron  thimbles 
should  be  provided.  Doors  in  it  should  be  so  located  that  direct  passage  is  secured 
to  the  firing  aisle,  and,  in  the  generator  room,  it  is  desirable  to  provide  a  gallery,  three 
or  four  feet  wide,  on  a  level  with  the  boiler-room  floor,  provided  the  main  operating 
room  is  not  at  this  level.  This  gallery  should  be  connected  with  stairways  to  the  main 
floors,  and  the  machine  galleries  when  practicable. 

In  some  modern  plants  the  high-tension  switches  are  housed  in  a  building  entirely 
separate  from  the  main  plant,  though  the  more  general  practice  is  to  place  them  in  a 
lean-to  adjoining  the  main  building  but  separated  from  it  by  partition  walls.  When 
these  switches  are  distributed  among  several  floors,  alongside  of  the  main  operating 
room,  large  windows  should  be  used  in  order  to  provide  a  maximum  of  light. 

Windows.  —  All  the  exterior  walls  of  the  plant  should  be  pierced  by  large  windows, 
preferably  glazed  with  ribbed  wire  glass  where  exposed  to  the  direct  rays  of  the  sun. 
The  other  windows  can  be  provided  with  plain  wired  glass,  although  this  is  not  generally 
done.  Ample  skylight  area  should  be  also  provided  for  the  boiler  and  engine  rooms.  If 
proper  skylight  construction  is  used  it  is  perfectly  practicable  entirely  to  avoid  leakage, 
and  this  is  of  the  utmost  importance  for  the  reason  that  electrical  machinery  located 
below  such  skylights  would  be  seriously  damaged  by  drip.  The  engine-room  monitor 
and,  in  some  cases,  the  boiler-room  monitor  are  glazed  throughout,  or  at  least  in  every 


BUILDING.  53 

other  panel.     These  sashes  should  be  either  of  the  swinging  or  sliding  variety  controlled 
from  the  floor  beneath. 

In  many  plants  wooden  window  sashes  and  door  frames  are  used,  on  account  of 
their  low  cost,  but  slightly  more  expensive  construction  of  wooden  frames  covered 
with  thin  tin  or  copper  is  better,  while  the  best  construction  calls  for  an  entirely 
metallic  sash  and  frame.  In  the  switchroom  the  outside  windows  may  be  provided 
with  fixed  sashes,  owing  to  the  danger  arising  from  any  foreign  material  blown  into 
the  room.  Before  this  was  realized,  some  prominent  plants  suffered  unexplained  shut- 
downs, due  to  trouble  with  switches  arising  from  refuse  blown  in  from  the  street.  If 
movable  sashes  are  used  in  such  rooms  secure  locking  devices  should  be  provided. 
The  openings  into  the  generator  room  should  be  fitted  with  windows  which  may  be 
opened  for  ventilating  purposes. 

Doors.  —  The  operating  and  boiler  rooms  should  be  provided  with  main  doors  of 
sufficient  size  to  enable  a  loaded  freight  car  to  enter  the  building  when  the  conditions 
permit  of  running  in  a  siding.  Where  it  is  impossible  to  obtain  railroad  service  of  this 
character,  or  for  other  reasons,  the  doorway  may  be  of  just  sufficient  size  to  admit  the 
largest  single  piece  of  machinery  at  a  time.  A  door  12  feet  wide  by  16  feet  high  will  admit 
a  railroad  car  and  anything  that  can  be  shipped  by  rail.  In  some  cases  Dutch  doors 
are  used,  of  which  the  upper  half  can  be  opened  for  ventilating  purposes,  the  lower 
portion  remaining  closed.  Where  it  is  desired  to  open  the  whole  door  at  once,  folding 
metallic  gratings  are  provided,  a  number  of  designs  for  which  are  on  the  market.  The 
doors  are  usually  built  of  hard  wood  with  bronze  hinges,  but  while  very  handsome  they 
are  not  fireproof.  They  can  be  sheathed  with  copper  or  some  other  thin  metal,  which 
makes  them  fireproof  for  all  practical  purposes.  In  some  cases  corrugated  or  sheet 
iron  doors  are  used.  Swinging  doors  are  for  many  reasons  inconvenient,  and  there 
are  a  number  of  designs  to  economize  room,  viz.,  sliding  doors,  vertical  or  horizontal 
sectional  folding,  swinging  and  rolling  shutter  doors. 

Ventilation.  —  Where  the  basement  of  the  building  is  below  the  ground  level  an 
area  should  be  excavated  around  the  building  for  light  and  ventilation.  This  area 
should  be  not  less  than  5  feet  wide,  and  protected  by  hand-rails  or  covered  with  iron 
gratings.  All  of  the  windows  in  the  lower  portion  of  the  building  should  preferably 
be  protected  by  iron  guards.  In  some  localities  it  has  been  found  necessary  to  cover 
the  windows  with  heavy  wire  screens  of  about  one- inch  mesh. 

The  ventilating  of  the  engine  room  practically  takes  care  of  itself,  owing  to  the  fact 
that,  in  order  to  house  the  machinery,  and  permit  the  installation  of  the  traveling 
crane,  it  must  have  a  certain  Height,  and  the  side  and  end  windows  of  the  monitor 
provide  a  means  of  exit  for  the  vitiated  air  at  the  point  where  it  is  most  liable  to 
collect.  The  ventilation  of  the  galleries  on  which  the  offices  and  switches  are  placed 
is  taken  care  of  by  the  windows  in  the  side  wall  and  the  sashes  opening  out  into  the 
operating  room.  The  engine-room  basement  is  well  cared  for  by  the  hatches  required 
for  handling  the  heavy  parts  installed  there  by  the  crane,  and,  where  reciprocating 


54 


STEAM-ELECTRIC    POWER    PLANTS. 


BUILDING. 


55 


engines  are  used,  the  revolving  field  extending  below  the  floor  level  acts  as  a  large  fan, 
producing  a  good  circulation  of  air.  For  closed  rooms  for  storage  batteries,  or  other 
purposes,  special  means  must  be  taken  to  provide  for  the  inlet  and  outlet  of  air,  special 
fans  and  ducts  being  put  in  for  this  purpose. 

The  boiler  room  is  often  neglected  in  regard  to  its  ventilation,  it  being  considered 
that  a  sufficient  change  of  air  is  produced  by  the  draft  required  for  the  boilers.  This, 
however,  is  not  the  case,  for  such  air  is  taken  from  the  lowest  level  of  the  room  and  leaves 
all  the  space  above  the  boilers  without  any  circulation  whatever.  As  this  portion  of 
the  room  receives  the  radiant  heat  from  the  boilers,  smoke  flues  and  pipes,  it  is  very 
uncomfortable  for  those  who  work  there.  The  worst  troubles  in  this  line  are  met  with 

1 


—•  ny?    B     iLcrag  fflSffl 

•Hflnr-tfiF!'  :          :ii     'fir,f^;nFy  !i    ESJarfn]  •!  IJIjUUUU  ffiRHfl 

.-.-^,-a^  l|ilfii|i!  f  In?"*  -Vf-"-'    i;|]i|!  || 

•UIBWMP  nntwuu  ur     jjnj  [J.LI >ui.c»du,t JJUULU 


Street  Kj.  Journal 


FIG.  6.     Structure  of  the  Delaware  Ave.  Plant,  Philadelphia. 


in  multi-story  buildings  having  overhead  coal  bunkers,  or  several  decks  of  boilers.  It 
is  desirable  that  large  gratings  should  be  installed  at  the  back  of  the  boilers,  so  that  the 
warm  air  can  escape  upward,  and  the  roof  and  bunker  construction  should  be  so 
designed  that  the  dead  spaces  below  the  sloping  sides  of  the  bunkers  are  well  ventilated 
by  louvres  or  windows.  The  monitor  for  the  bunkers  should  be  glazed  where  con- 
veyor machinery  is  installed,  the  best  practice  being  to  place  alternate  windows  and 
louvres  in  this  portion  of  the  plant,  providing  sufficient  ventilation  and  light.  Where 
portions  of  the  boiler  room  are  covered  by  flat  roofs,  metal  ventilators  should  be  put 
in  to  permit  the  free  circulation  of  air.  In  some  plants  buildings  have  been  designed 
without  monitors,  and  under  such  circumstances  ornamental  ventilating  towers  are 


STEAM-ELECTRIC    POWER    PLANTS. 


provided  at  suitable  points. 
Europe. 


This  latter  practice,  however,  is  typical  of  continental 


Stairways  and  Elevators.  —  Ample  stairway  provision  should  be  made  at  all  points, 
since  easy  access  to  all  portions  of  the  plant  is  essential.  These  stairways  should  be 
designed  of  ample  width  (at  least  3  to  4  feet)  and  with  easy  steps  and  straight  risers 
broken  by  landings,  for  the  reason  that  many  times  it  is  necessary  to  carry  long  pipes 
and  other  apparatus  up  and  down  such  passageways.  In  many  plants  the  mistake 
has  been  made  of  using  winding  stairs,  making  it  necessary  to  rig  a  block  and  tackle, 
or  use  the  traveling  crane  to  elevate  material  into  the  galleries.  Stairs  should  be  built 
with  steel  framing,  the  treads  and  risers  being  either  cast  iron,  checkered  steel  or 
slate.  In  some  cases  the  treads  are  covered  with  rubber  strips  or  anti-slip  material. 
All  the  important  stairways  should  have  closed  risers,  while  the  small  stairways  lead- 
ing to  light  galleries  and  windows  may  simply  be  steps  without  risers. 

In  some  large  modern  plants  where  the  operating  offices  are  located  on  the  upper 
floors,  passenger  elevators  are  installed,  but  it  is  more  usual  to  provide  only  a  freight 
elevator,  generally  located  in  the  boiler  rooms  of  double  decked  plants. 

Toilets  and  Plumbing.  —  Another  neglected  portion  of  the  equipment  is  that  of 
toilets,  baths  and  lockers.  The  lockers  should  be  conveniently  situated  near  the 


FIG.  7.     L  Street  Plant,  Boston. 

portions  of  the  building  in  which  the  different  working  forces  are  employed,  and  the 
toilets  and  baths  should  be  located  close  to  the  lockers,  enabling  the  men  to  change 
their  clothes,  clean  up  conveniently,  etc.  The  lockers  should  be  large  enough  to  con- 


BUILDING. 


57 


58  STEAM-ELECTRIC    POWER    PLANTS. 

tain  a  complete  change  of  clothing,  permitting  the  men  in  winter  to  hang  up  over- 
coats, while  sufficient  room  should  be  allowed  in  the  aisles  to  allow  the  men  to  make 
the  necessary  changes. 

The  plumbing  should  be  of  good  substantial  quality,  preferably  exposed  work, 
enameled  iron  basins,  bowls  or  sinks.  Bowls  for  this  purpose  are  more  preferable  than 
sinks,  on  account  of  the  considerable  saving  of  wash-water,  which  is  an  important 
factor  in  the  operation  of  large  plants.  The  toilet-room  floors  should  be  tiled  and  the 
partitions  of  white  enamel  slate  or  (if  more  expensive  construction  is  desired)  marble. 
The  advantage  of  white  finish  is  that  it  enforces  cleanliness  by  making  dirt  conspicu- 
ous. The  drains  should  be  run  to  avoid  all  ducts  and  wiring  and  preferably  should 
discharge  into  some  sewage  system,  never  into  the  circulating  water  discharge,  although 
this  is  sometimes  done. 

Heating  and  Lighting.  —  In  temperate  latitudes  it  is  necessary  to  provide  for  the 
heating  of  the  building  in  winter  by  the  installation  of  radiators  or  coils  at  suitable 
points,  or  hot-air  supply  forced  to  the  various  portions  of  the  building  through  ducts. 

The  house  wiring  for  light  should  be  run  entirely  in  iron  armored  conduit ;  in  cases 
where  practicable,  in  the  wall  or  concrete  floor.  In  the  walls,  chases  should  be  pro- 
vided for  all  risers  necessary  for  the  house  service,  exposed  pipes  being  very  unsightly. 

Roof.  — The  cheapest  roof  construction  is  boards  covered  with  roofing  felt,  on  which 
is  laid  a  pitch  and  gravel  roof.  It  is  important  that  no  leakage  should  take  place,  espe- 
cially in  the  generating  room,  and  there  are  several  different  specifications  for  slag  and 
gravel  roofing.  This  roof  is  suitable  for  slopes  ranging  from  two  inches  per  foot  up  to 
45°,  but  is  preferably  applied  to  the  flatter  slopes,  for  steep  inclines  increase  materially  the 
expense  of  applying  it.  The  principle  of  such  a  roof  built  of  boards  is  that  although 
it  is  not  fireproof,  it  has  considerable  fire-resisting  properties  if  properly  constructed. 
This  slag  and  gravel  roof  is  also  often  applied  to  reinforced  concrete  slabs  or  arches. 
In  continental  Europe,  pumice  stone  is  occasionally  used  in  concrete  for  roof  pur- 
poses. In  America  cinder  concrete  is  often  used  instead  of  gravel.  Both  of  these 
concretes  are  much  lighter  than  the  ordinary  gravel  concrete. 

In  constructing  a  gravel  roof  the  concrete  is  first  covered  with  a  layer  of  hot  pitch, 
over  which  is  laid  the  tarred  roofing  felt,  the  sheets  lapping  over  each  other  about 
half  the  width  of  the  roll,  and  each  sheet  being  mopped  with  pitch  as  it  is  laid.  Over 
this  tarred  felt  another  layer  of  pitch  is  applied,  on  which  roofing  felt  is  again  spread, 
usually  a  triple  layer,  each  sheet  being  coated  with  pitch  as  laid.  Over  the  entire 
surface  an  even  layer  of  pitch  is  then  spread,  in  which,  while  still  hot,  slag  or  gravel  is 
embedded.  For  architectural  reasons  it  is  sometimes  desirable  to  use  different  roof 
construction,  and  the  following  methods,  while  they  greatly  enhance  the  appearance 
of  the  building,  add  considerably  to  its  expense  of  construction.  Upon  concrete  slabs 
standing  seam  copper  roofing  is  applied.  This  makes  a  very  handsome  finish  and 
never  requires  to  be  painted,  the  copper  after  a  short  while  oxidizing  to  an  artistic  color. 
Another  well-designed  roof  requires  a  preliminary  preparation  in  regard  to  the  steel 


STRUCTURAL  STEEL.  59 

work,  in  the  shape  of  "T"  irons  laid  over  the  roof  purlins.  Between  these  book  tiles 
are  laid,  covered  by  Spanish  roll  tile,  of  a  uniform  dark  color.  The  advantage  of  the 
concrete  roof  construction,  and  the  two  latter  methods  mentioned,  is  that  they  are 
entirely  fireproof.  Steep  inclines  are  necessary  for  any  tile  or  metallic  roof,  and  the 
height  should  be,  at  least,  one-third  of  the  span.  All  roofs  should  be  provided  with 
gutters  on  the  eaves  and  leaders  connecting  with  the  drains.  Where  flat  roofs  are  used, 
surrounded  by  parapet  walls,  metal  flashing  should  be  provided. 

For  tropical  countries  the  pitch  and  gravel  roofs,  so  frequently  used  in  the  temperate 
zones,  are  not  suitable,  a  special  material  being  prepared  for  use  in  such  climates.  In 
the  earthquake  zone  corrugated  iron  buildings  are  erected,  the  sheets  lapping  over  each 
other  five  inches  and  from  one  and  a  half  to  two  inches  on  the  side.  These  sheets  are 
turned  down  over  the  end  of  the  building  to  give  a  cornice  effect,  and  the  peak  of  the 
roof  is  held  by  a  prepared  ridge  roll  which  is  supplied  with  it.  In  some  cases  painted 
corrugated  sheets  are  used,  owing  to  their  cheapness  of  cost.  The  material  should 
preferably  be  galvanized,  in  which  condition  it  should  not  receive  a  coat  of  paint  until 
it  is  exposed  to  the  weather  one  or  two  years,  and  the  surface  has  become  slightly  oxi- 
dized. One  of  the  troubles  with  corrugated  iron  roofing  arises  from  its  making  an  oven 
out  of  the  building  which  it  covers,  unless  an  air  space  is  provided  to  insulate  the  room 
directly  below  the  roof  from  the  heat,  which  may  be  done  by  applying  sheathing  on 
the  bottom  chords  of  the  roof  trusses.  This  sheathing  reduces  the  height  of  the  room 
and  increases  somewhat  the  difficulty  of  ventilating  it  properly.  Another  trouble 
with  corrugated  iron  roofs  arises  from  the  condensation  of  moisture  upon  their  sur- 
face when  the  roof,  from  any  reason,  becomes  cooler  than  the  air.  This  moisture 
occasionally  dripping  into  the  room  below  may  cause  trouble  with  electrical  machinery. 

Leaders.  —  One  square  inch  of  leader  area  is  usually  provided  for  each  100  to  150 
square  feet  of  roof.  The  leaders  should  never  be  smaller  than  four  inches  in  diameter. 
In  ordinary  buildings  galvanized  iron  leaders  are  used,  while  in  more  pretentious  plants, 
copper  of  rectangular  shape  is  sometimes  employed.  All  leaders  should  be  provided 
on  their  upper  ends  with  removable  guards  or  strainers. 

STRUCTURAL  STEEL. 

Roof  Construction.  — •  In  modern  power  plants  the  tendency  towards  fireproof  con- 
struction at  all  points  displaces  the  wooden  roof  truss,  once  so  common,  by  those  of 
steel.  The  outline  of  the  truss  depends  upon  the  kind  of  a  roof  to  be  supported  and 
the  slope  adopted,  the  slope  depending  usu'ally  upon  architectural  considerations, 
while  the  material  used  for  the  roof  is  governed  in  part  by  the  slope.  When  slate 
or  shingles  were  the  only  roofing  materials  available,  steep  slopes  were  necessary  in 
order  to  shed  water  rapidly  and  prevent  it  working  up  under  the  roofing  and  causing 
leaks,  while  with  modern  methods  of  waterproofing  a  slope  of  two  inches  per  foot 
is  sufficient  to  supply  the  requisite  drainage.  Such  roofs  are  advantageous  in  many 
ways,  require  less  material  than  the  steeper  pitches,  are  easier  to  build,  and  present 


6o 


STEAM-ELECTRIC    POWER    PLANTS. 


no  difficulties  in  the  application  of  the  waterproof  covering.  Steeper  roofs  are,  how- 
ever, often  used,  owing  to  the  fact  that  they  are  considered  more  economical  in  steel, 
but  this  advantage  is  more  than  balanced  by  the  additional  cost  of  applying  the 
roofing.  In  practice  the  pitch  of  the  roof  is  governed  by  the  architectural  effect  and 
by  the  skylight  construction. 

In  small  plants  roof  trusses  are  often  supported  by  the  walls  of  the  building,  which 
are  stiffened  by  pilasters  at  the  points  where  the  trusses  are  set,  anchor  bolts  being  used 


•I* E.  <}  u  a.  I     P  an  c  1  &  


to  prevent  longitudinal  or  lateral  slipping.  The  top  chords  of  the  trusses  are  tied 
together  by  the  purlins,  which  support  the  roof,  and  in  deep  trusses  the  lower  chords 
are  often  connected  by  longitudinal  bracing  at  some  of  the  panel  points.  In  addition, 
at  the  end  panels,  and  in  long  buildings  at  intermediate  panels,  angles  or  rods  are  used 
for  diagonal  bracing  in  the  plane  of  the  upper  and  lower  chords. 

The  accompanying  sketch,  Fig.  i,  illustrates  some  of  the  more  usual  forms  of 
roof  trusses,  and  the  various  cross-sections  of  power  plants  shown  in  this  volume 
will  suffice  to  illustrate  other  forms  of  trusses  in  actual  use.  In  designing  a  roof  truss 
it  is  necessary  to  know  the  distance  between  the  trusses,  the  span  and  the  load.  In 
power  plant  work  the  location  of  columns  is  largely  determined  by  the  equipment, 
and  it  is  desirable,  for  the  sake  of  rigidity,  to  have  the  trusses  connect  directly  with  the 
columns.  It  will  be  seen  that  the  span  and  the  distance  between  the  trusses  are  fixed, 
and  that  these  distances  may  or  may  not  be  such  as  will  permit  the  best  economy  of 
steel  work.  The  loading  depends  upon  the  locality  of  the  plant  and  the  roof  to  be 
used.  In  New  York  City  the  live  load  for  a  roof  having  a  pitch  of  less  than  20°  is 


STRUCTURAL    STEEL.  6 1 

50  pounds  per  square  foot,  and  for  pitches  exceeding  20°  is  30  pounds  per  square  foot. 
This  live  load  is  the  vertical  component,  on  the  projected  area  of  the  roof,  of  the  snow 
and  wind  loads.  In  localities  subject  to  severe  wind  storms  it  is  necessary  so  to  secure 
the  roof  to  the  building  that  it  will  not  be  lifted  by  storms.  In  some  cases  the  roof 
trusses  are  made  heavy  enough  to  support  small  bunkers  or  coal  pockets,  either  con- 
tinuous throughout  the  length  of  the  building,  or  individual  pockets  suspended  in  front 
of  each  boiler.  In  addition,  the  trusses  must  be  of  sufficient  strength  to  permit  of  the 
steam  piping  being  hung  from  them,  and  to  carry  the  coal  conveyor.  In  some  plants 
the  breeching  or  smoke  flue  from  the  boilers  is  suspended  from  the  roof  trusses. 

Crane  Runway.  —  An  overhead  crane,  operated  by  power  or  hand,  is  a  necessity 
in  the  engine  room.  In  brick  buildings  the  runway  girders  are  often  supported  on 
pilasters  on  the  walls,  designed  for  this  purpose.  This  type  of  construction,  how- 
ever, is  only  adapted  to  comparatively  low  structures,  in  locations  where  masonry  is 
cheaper  than  steel  framing. 

Building  Material.  —  In  localities  where  building  materials  are  expensive  it  is  often 
cheaper  to  erect  a  corrugated  iron  sheathed  steel  frame  structure  than  it  is  to  put 
tip  one  of  brick  or  concrete,  this  being  particularly  the  case  in  countries  where  the 
labor,  as  well  as  the  building  material,  has  to  be  imported.  A  very  cheap  and  tem- 
porary structure  can  be  put  up  with  a  wooden  frame  covered  with  corrugated  iron. 
For  these  types  of  buildings,  galvanized  corrugated  iron  is  used,  Nos.  18  to  24  gauge 
for  the  roof  and  Nos.  20  to  26  gauge  for  the  siding  (U.  S.  Standard  gauge  is  used  in 
the  United  States),  and  black  or  painted  sheets  are  occasionally  used,  but  since  they 
are  not  so  durable  as  the  galvanized  sheets  their  use  cannot  be  recommended.  The 
siding  is  in  all  cases  two  gauges  lighter  than  the  roofing.  The  best  grade  of  this 
material  is  called  "muck  bar"  corrugated  sheeting,  and  is  much  more  durable  where 
exposed  to  moist  air  than  the  ordinary  grades,  particularly  near  salt  water.  A  cor- 
rugated iron  building  can  hardly  be  classed  as  a  permanent  structure,  and  cannot 
be  recommended  for  power  plant  purposes  owing  to  the  fact  that  moisture  is  liable 
to  gather  on  the  lower  surface  of  the  roofing  and  drip  on  the  machinery.  This  is 
preventable  by  cork  paint. 

There  are  several  methods  in  use  for  the  design  of  steel  frame  buildings,  in  one  the 
frame  is  entirely  self-supporting  and  the  light  curtain  walls  enclosing  the  building  are 
supported  on  the  steel  work.  In  another  method  the  walls  are  self-supporting,  and 
the  steel  frame,  while  at  the  same  time  self-supporting,  is  to  a  certain  extent  braced  by 
the  walls  which  encase  the  outer  rows  of  columns  and  the  row  between  the  boiler  and 
engine  rooms.  In  low  buildings  the  walls  between  the  columns  are  usually  light 
curtain  walls  of  brick  or  concrete. 

Framing.  —  In  large  plants  located  on  valuable  ground,  of  which  it  is  essential  to 
utilize  the  entire  area  to  the  best  advantage,  double  and  even  three  deck  boiler  rooms  are 
sometimes  required,  above  which  it  is  necessary  to  have  sufficient  bunker  capacity  to  tide 


62 


STEAM-ELECTRIC    POWER    PLANTS. 


the  plant  over  short  interruptions  in  the  fuel  supply,  and  in  some  plants  the  chimneys 
have  been  supported  on  platforms  above  the  firing  aisles.  In  such  plants  the  boilers  are 
supported  on  the  building  columns,  which  in  the  boiler  room  are  spaced  to  suit  them, 
and  the  columns  in  the  engine  room  are  arranged  so  that  the  bays  there  correspond, 
the  columns  being  placed  on  the  center  lines  of  the  batteries  of  boilers,  or  on  the  center 


T 


FIG.  2. 


//    '   '    '  '    ' 
'  '    '   '   "  '  ' 


FIG.  3.    Crane  Column. 


line  of  the  space  between  the  batteries.  The  steel  frame  of  this  class  of  building  must 
be  designed  to  suit  the  purpose  of  the  building  and  to  permit  of  economical  operation; 
unobstructed  passages  and  walkways  are  necessary  at  a  number  of  points;  the  floor 
framing  must  be  designed  to  permit  numerous  openings  for  pipes,  coal  and  ash  chutes, 
conveyors,  etc.  For  this  reason  it  is  desirable  that  all  floor  beams  and  girders  should 
be  located  in  vertical  planes,  even  should 
such  an  arrangement  not  conduce  to  the 
greatest  economy  of  steel;  cross  or  "X" 
bracing  is  not  usually  permissible,  except 
where  it  will  be  encased  in  permanent  walls, 
portal  bracing  being  preferable.  It  will 
usually  be  found  impossible  entirely  to 
avoid  "X"  bracing,  and  in  such  cases 
portal  braced  panels  should  be  introduced 
at  intervals,  in  order  to  provide  for  passage- 
ways. In  the  boiler-room  basement  "X" 
bracing  should  not  be  permitted  under  any  circumstances,  as  this  portion  of  the 
building  is  usually  reserved  for  feed- water  pumps,  heaters  and  other  small  auxiliary 
machinery,  together  with  various  lines  of  pipes,  and  it  is  essential  that  clear  and 
unobstructed  passages  be  left  for  the  safety  of  the  operating  force. 

Type  of  Columns.  —  In  regard  to  the  details  of  design,  all  of  the  sections  used 
should  be  open  sections  (as  indicated  in  Figs.  2  and  3),  accessible  at  all  points, 
except  where  encased  in  brick  or  concrete,  for  inspection  and  painting;  that  is, 
box  girders  or  columns  should  be  avoided.  In  a  great  many  structures,  col- 
umns built  up  of  channels  and  plates  are  used;  in  fact,  this  section  is  a  favorite 
for  heavy  columns,  owing  to  its  low  shop  cost,  but  its  great  disadvantage  arises  from 
the  fact  that  the  interior  of  the  column  cannot  be  inspected  or  repainted.  In  boiler 
rooms,  sections  of  this  character  are  particularly  undesirable,  owing  to  the  fact  that, 
in  such  a  location,  there  is  more  likelihood  of  corrosion  occurring  inside  of  the  columns 
than  outside.  In  some  structures  such  columns  have  been  filled  with  concrete  after 
erection,  and  this  practice  is  preferable  to  leaving  them  empty. 


STRUCTURAL    STEEL.  63 

Floor  Loads.  —  Brick,  terra  cotta,  concrete  or  reinforced  concrete  floor  construc- 
tion is  employed  in  important  plants,  and  the  floor  system  must  be  designed  to  support 
it  and  the  superimposed  live  load.  In  many  cases  it  will  be  found  that  the  floors  are 
subjected  to  concentrated  local  loads  at  various  points  which  require  special  treatment. 
In  other  cases  railroad  tracks  or  sidings  must  be  extended  into  the  building,  in  order  to 


FIG.  4.     Steel  Structure  of  the  General  Electric  Co.'s  Plant,  Schenectady,  N.Y. 

facilitate  the  delivery  of  the  heavy  machinery  in  cars,  at  a  point  where  it  can  be  reached 
by  the  traveling  crane,  while  sometimes  heavy  machinery  is  carried  on  the  floors,  boiler 
settings,  stokers,  ash  hoppers,  etc.  The  live  load  for  which  the  floors  are  designed 
depends  upon  the  heaviest  piece  of  machinery  which  will  be  laid  on  them  or  moved 
over  them  on  skids  or  rollers.  The  Interborough  power  plant  on  West  59th  Street, 
in  New  York  City,  was  designed  for  the  following  live  floor  loads,  in  addition  to  the 
dead  loads: 

LB.  PER 
SQ.  FOOT. 

Boiler-room  floor 250 

Engine-room  floor 400 

Operating  platform  around  boilers      100 

Mezzanine  over  boilers      150 

Upper  switchboard  floor 300 

Lower  switchboard  floor 400 

In  addition,  local  concentrated  loads  were  considered,  and  in  some  cases  the  floors 
were  designed  to  suit  the  actual  loads  imposed  on  them.  In  this  plant  5,000  K.W., 


64  STEAM-ELECTRIC    POWER    PLANTS. 

11,000  volt  generators  were  installed,  driven  by  twin  horizontal- vertical  engines. 
In  some  other  plants  floor  loads  are  as  high  as  600  pounds  per  square  foot,  and  some- 
times even  higher  loads  have  been  taken  into  account  in  designing  the  floor  system. 
Except  during  the  construction  period  there  is  very  little  likelihood  of  the  actual  floor 
loads  ever  approaching  these  figures,  but  during  this  period,  when  material  and 
machinery  are  being  handled  and  unpacked,  large  quantities  of  heavy  material  are 
liable  to  be  piled  up  on  any  part  of  the  floor,  and  it  may  very  easily  happen  that  the 
designed  floor  loads  are  exceeded,  unless  particular  care  is  taken  to  guard  against  such 
occurrences. 

Fiber  Stresses.  —  Steel  structures  are  proportioned,  in  regard  to  the  sections  used,  by 
a  limit  set  on  the  unit  fiber  stress  in  tension,  which  is  reduced  for  compression  members, 
usually  by  Gordon's  formula.  In  many  localities  the  limiting  unit  stresses  are  specified 
in  the  building  laws,  these  in  some  cases  being  limited  in  their  application  to  some  par- 
ticular city,  while  in  other  cases  they  apply  to  a  state  or  nation.  As  the  legal  require- 
ments differ  greatly  in  different  localities,  it  is  advisable  to  investigate  the  subject, 
unless  these  are  well  known.  In  practice,  the  fiber  or  unit  stresses  used  vary  from 
13,500  to  20,000  pounds  per  square  inch  in  tension  for  steel  and  for  most  of  the 
important  structures  the  working  stresses  have  been  kept  between  15,000  and  16,000 
pounds  per  square  inch. 

Expansion  Joints. — -In  very  long  buildings  the  expansion  due  to  changes  of  temper- 
ature must  be  taken  care  of  during  erection,  but  such  precautions  are  not  required  in 
small  buildings.  The  Rapid  Transit  power  house  on  West  59th  Street,  New  York  City, 
is  693  feet  10  inches  long,  and  is  divided  in  three  nearly  equal  sections  by  two  traverse 
planes,  at  which  expansion  joints  are  located,  the  ends  of  all  longitudinal  members  in  one 
section  are  riveted,  while  those  in  the  other  sections  are  bolted  through  slotted  holes 
which  allowed  for  a  temperature  variation  of  two  inches.  In  buildings  under  three 
hundred  feet  in  length  temperature  variations  do  not  cause  much  trouble  and  no  special 
precautions  are  required  to  care  for  them.  Where  expansion  joints  are  used  in  buildings 
it  is  sometimes  specified  that  after  the  building  has  been  walled  in  the  joints  shall  be 
blocked  with  lead  to  prevent  any  motion  in  the  steel  work  cracking  the  concrete  floor- 
ing, etc.  The  necessity  of  these  joints  is  only  during  the  erection  period  when 
longitudinal  expansion  is  very  liable  to  make  it  difficult  to  erect  portions  of  the  steel 
work. 

Column  Base.  —  The  columns  are  preferably  designed  with  a  base  of  sufficient 
area  to  permit  of  their  being  set  directly  upon  the  foundation,  but  cast-iron  base 
plates  are  often  interposed  at  this  point  as  they  can  be  leveled  up  before  the  column 
is  erected.  Grillages  are  undesirable,  but  cannot  be  avoided  with  heavy  column  loads. 
The  general  practice  is  to  rest  the  columns  on  the  foundations,  depending  upon  the 
bracing  and  floors  to  give  the  structure  stiffness  and  its  weight  to  hold  it  down  and 
prevent  lateral  motion,  assisted  by  the  concrete  encasing  the  grillage  and  base  of  the 


STRUCTURAL    STEEL.  65 

column.  In  power  plants  it  is  desirable  to  have  the  structure  rigidly  secured  to 
the  foundation  by  bolts,  the  foundation  being  preferably  a  mat  under  the  entire 
structure  instead  of  a  number  of  isolated  piers,  for  such  a  construction  makes  a  very 
rigid  building. 

Floor  Beams,  etc.  —  The  use  of  floor  arches  causes  a  lateral  thrust  against  all  of 
the  beams  composing  the  floor  system,  and  for  this  reason  it  is  necessary  to  introduce 
tie  rods  suitably  spaced  to  take  care  of  this  stress.  These  tie  rods  should  always  be 
placed  high  enough  so  that  they  will  be  hidden  by  the  floor  arches,  as  this  adds 
greatly  to  the  appearance  of  the  ceilings.  In  some  plants  this  detail  has  been 
neglected  and  the  result,  to  say  the  least,  is  not  sightly.  Another  small  point  is  the 
provision  of  curb  angles  around  all  hatches  and  other  openings  in  the  floors,  which 
should  project  from  one  to  two  inches  above  the  finished  floor  level,  their  purpose 
being  to  prevent  wash-water,  sweepings,  etc.,  going  down  to  the  floor  below.  The 
value  of  these  curbs  is  more  apparent  in  those  cases  where  machinery  is  located  on 
the  lower  floors  or  under  the  galleries  and  liable  to  damage  from  anything  falling 
into  it. 

Structural  Steel  of  Recent  Plants.  —  The  following  comparison  of  the  amount  of 
steel  in  some  recent  power  plants  may  be  of  interest: 


NAME  OF  PLANT. 

Tons  of 
Steel. 

K.W. 

Normal. 

K.W. 

Tons  of 
Steel  per 
Sq.  Foot. 

Tons  of 
Steel  per 
Cu.  Foot. 

Chelsea        

6,000 

?  7,700 

.104 

.076 

.0007 

Interborough  

12,300 

6o,OOO 

.20? 

.088 

.0008 

Potomac  

800 

IO,OOO 

.04.2 

.027 

.0001; 

Port  Morris     . 

2.8oo 

30.000 

.OOd. 

.07!; 

.0000 

The  plants  referred  to  in  the  above  table  are  the  Chelsea  plant  of  the  Underground 
Electric  Railway  Co.,  London,  England;  the  West  59th  Street  power  house  of  the 
Interborough  Rapid  Transit  Co.,  New  York;  the  Port  Morris  power  house  of  the 
New  York  Central  Railroad  Co.,  New  York,  and  the  plant  of  the  Potomac  Electric 
Power  Co.,  Washington,  D.C.  The  Chelsea  plant  has  a  double  decked  boiler  room 
with  overhead  coal  bunkers  and  horizontal  turbines.  The  Interborough  plant  has  a 
single  decked  boiler  room,  economizer  floor  over  boilers,  overhead  bunkers,  chimneys 
carried  on  platforms  over  the  firing  aisle,  and  horizontal-vertical  twin  engines.  The 
Port  Morris  plant  has  a  single  decked  boiler  room  with  overhead  bunkers,  the  stacks 
being  carried  as  in  the  Interborough  plant,  and  vertical  turbines.  In  each  case  the 
boiler  room  is  parallel  with  the  engine  room.  The  Potomac  plant  has  the  boiler  room 
at  right  angles  with  the  engine  room,  is  designed  for  vertical  turbines,  and  has  a  single 
decked  boiler  room  with  overhead  bunkers.  The  chimneys  in  this  and  the  Chelsea 
plant  extend  to  the  ground. 

Workmanship.  —  The  following,  in  reference  to  workmanship,  is  based  on  the 
standard  practice  of  some  of  the  leading  concerns.  All  material  should  be  punched 
one-sixth  of  an  inch  larger  than  the  nominal  size  of  the  rivets,  except  that  material 


66  STEAM-ELECTRIC    POWER    PLANTS. 

five -eighths  of  an  inch  thick  and  over  must  be  drilled  or  sub-punched  and  reamed  one- 
eighth  of  an  inch  larger  in  diameter,  so  as  to  remove  all  sheared  or  burred  edges.  In 
some  cases  sub-punching  is  insisted  upon  when  more  than  one  cover  plate  is  used  on 
columns  or  girders,  in  which  case  the  reaming  must  be  done  after  the  parts  are 
assembled  and  clamped  together. 

All  work  must  match  so  accurately  that,  after  assembling,  the  rivets  can  be  entered 
without  drifting. 

Wherever  possible  all  rivets  should  be  machine  driven  by  direct  acting  machines, 
operated  by  compressed  air,  steam  or  hydraulic  pressure,  which  shall  be  capable  of 
retaining  the  applied  pressure  after  the  upsetting  has  been  completed.  Field  riveting 
shall  be  done,  preferably,  by  long  stroke  pneumatic  riveters.  Hand  riveting  must  not 
be  permitted  for  rivets  over  seven-eighths  of  an  inch  in  diameter. 

The  details  shall  be  designed  to  avoid  riveting  in  difficult  or  inaccessible  places. 
No  bolts  should  be  used,  except  by  permission ;  they  should  be  turned  to  a  driving  fit 
and  the  bolt  holes  should  be  drilled  and  reamed  after  the  parts  are  assembled  and 
clamped  together.  In  many  cases,  however,  the  roof  purlins  are  bolted,  all  other 
connections  being  riveted. 

The  abutting  surfaces  of  compression  members  should  be  truly  faced  to  an  even 
bearing.  In  some  cases  this  clause  is  extended  to  cover  the  tops  of  column  bed-plates 
in  a  specific  manner,  and  in  some  rare  instances  it  is  specified  that  the  abutting  ends 
of  tension  members  shall  be  faced. 

All  rivets  when  heated  and  ready  for  driving  must  be  clean.  When  driven  they 
must  completely  fill  the  hole  and  have  round  concentric  heads  of  uniform  size, 
thoroughly  pinching  the  connected  pieces  together. 

Inspection.  —  All  facilities  for  the  inspection  and  testing  of  material  and  workman- 
ship should  be  furnished  by  the  contractor  to  duly  appointed  inspectors,  but  the  inspec- 
tion for  the  raw  materials  should  be  made  at  the  mills  or  foundries  where  the  steel  is 
rolled  or  the  castings  made.  The  inspectors  should  be  allowed  free  access  to  all  portions 
of  the  plant  in  which  any  portion  of  the  material  is  made. 

Painting.  —  In  regard  to  painting  there  arc  a  number  of  differing  requirements,  raw 
and  boiled  linseed  oil,  iron  ore  or  iron  oxide  paint,  red  lead  paint,  graphite  paint,  etc., 
and  there  are  a  number  of  proprietary  mixtures  on  the  market  of  more  or  less  value. 
The  proportion  of  the  materials  to  be  used  in  preparing  the  paint  and  the  kind  of 
brushes  to  be  used  in  applying  it  are  sometimes  specified.  The  proportion  of  red  lead 
used  varies  from  sixteen  to  forty  pounds  per  gallon  of  oil,  depending  upon  the  quality; 
a  paint  containing  twenty-five  pounds  of  red  lead  per  gallon  of  oil  makes  a  very  satis- 
factory coating  for  steel,  the  following  formula  being  a  very  good  mixture: 

25  pounds  of  pure  red  lead. 
i  gallon  of  pure  raw  linseed  oil. 
J  pint  of  japan,  free  from  benzine. 


STRUCTURAL    STEEL.  67 

Iron  ore  or  oxide  paints  possess  the  merit  of  being  cheap,  and  for  this  reason  are  much 
used,  but  in  practice  they  are  not  reliable  and  should  be  avoided.  Boiled  linseed  oil 
makes  a  good  coating  for  iron  or  steel  without  a  pigment.  The  pigment  addition  acts 
as  a  filler  for  the  pores  in  the  oil  and  retards  its  drying,  and  for  this  reason  driers  are 


u  y  u.u 


FIG.  5.     Structure  of  the  Williamsburg  Plant,  Brooklyn  (Street  Railway  Journal). 

used,  japan  being  one  of  the  best  materials  for  this  purpose,  provided  it  is  free  from 
benzine.  The  use  of  benzine,  gasolene  or  naphtha,  should  not  be  permitted  in  any 
paint  which  is  to  be  applied  to  ironwork,  for  the  rapid  evaporation  of  the  benzine 
will  cool  the  material  to  a  point  where  the  surface  to  be  painted  will  be  covered 
with  dew  or  moisture  deposited  from  the  atmosphere. 


68  STEAM-ELECTRIC    POWER    PLANTS 

At  least  forty-eight  hours  should  elapse  between  the  application  of  each  coat  of 
paint,  and  painting  should  not  be  permitted  during  freezing  or  wet  weather.  In 
riveted  work  all  surfaces  coming  in  contact  should  be  painted,  before  assembling,  with 
one  coat  of  paint  on  each  surface.  Occasionally  it  is  specified  that  all  portions  of  the 
work  to  be  embedded  in  concrete  or  brickwork  shall  receive  one  or  two  coats  of  asphal- 
tum  varnish.  All  the  work  should  receive,  at  least,  one  coat  of  paint  before  it  is  shipped, 
and  after  erection  all  places  where  the  paint  has  been  rubbed  off  as  well  as  the 
heads  of  field  rivets  should  be  painted,  after  which  the  entire  structure  should  receive 
two  coats  of  paint. 

There  is  very  little  agreement  in  regard  to  the  best  coating  for  any  particular  case, 
probably  because  so  much  depends  upon  the  preparation  of  the  surface  to  receive  the 
paint,  the  care  with  which  it  is  applied  and  the  exposure  conditions.  All  rust  and 
loose  scale  should  be  removed  before  the  paint  is  applied,  and  the  painter  should  follow 
immediately  after  the  cleaner. 

Insulation  of  Steel  Frame.  —  At  various  times  it  has  been  proposed  to  insulate  the 
steel  frames  of  power  houses,  with  the  idea  of  preventing  electrolytic  action.  The 
complete  insulation  of  the  frame  is  impractical,  owing  to  the  fact  that  a  number  of  pipes 
must  be  supported  by  hangers  bolted,  or  otherwise  secured,  to  the  framing,  some  of 
these  pipes  being  in  connection  electrically  with  the  ground  water,  and  an  attempt  at 
insulation  is  extremely  liable  to  localize  the  electrolytic  action  at  a  few  points,  which 
would  be  worse  than  the  troubles  arising  from  the  entire  omission  of  insulation. 

At  the  site  of  erection,  or  adjacent  thereto,  it  is  usually  necessary  to  store  portions 
of  the  structural  material,  after  it  is  unloaded  and  until  it  is  required  for  erection. 
This  material  should  be  laid  on  skids,  well  out  of  contact  with  the  ground. 

Character  of  Steel. — A  large  portion  of  the  structural  steel  made  in  the  United  States 
is  made  under  the  "Manufacturers'  Standard  Specifications"  as  revised  to  Feb.  6,  1903, 
which  permits  the  use  of  either  open-hearth  (Siemens-Martin)  or  Bessemer  steel  (the 
Bessemer  steel  produced  in  the  United  States  is  made  by  the  acid  process,  no  basic  Bes- 
semer steel  being  produced) ;  the  practice,  however,  is  growing  of  specifying  open-hearth 
steel  exclusively  for  most  structures,  owing  to  the  fact  that  it  is  more  regular  in  regard 
to  its  physical  properties.  Bessemer  steel,  on  the  contrary,  is  liable  to  fail  in  service, 
in  an  irregular  and  inexplicable  manner,  and  for  this  reason  it  is  not  desirable  for 
structural  work. 

The  following  in  regard  to  the  quality  of  the  material  to  be  used  for  structural  steel 
covers  the  best  practice,  being  made  up  from  the  "Manufacturers'  Standard  Specifica- 
tions" with  modifications  based  on  good  authorities. 

All  steel  must  be  made  by  the  open-hearth  process.  The  phosphorus  must  not 
exceed  0.08  per  cent.  The  steel  shall  be  of  uniform  quality,  tough  and  ductile. 

Rivet  steel  shall  have  an  ultimate  tensile  strength  of  from  45,000  to  55,000 
pounds  per  square  inch.  Structural  steel  shall  have  an  ultimate  tensile  strength  of 
from  55,000  to  65,000  pounds  per  square  inch.  The  elastic  limit  should  not  be  less 


ARCHITECTURAL  FEATURES.  69 

than  one-half  of  the  ultimate  tensile  strength.  The  percentage  of  elongation  shall  be 
equal  to 

1,400,000 
Ultimate  strength  in  pounds  per  square  inch 

Rivet  steel,  before  or  after  heating  to  a  light  yellow  heat  and  quenching  in  cold  water, 
must  stand  bending  180°  flat  on  itself  without  signs  of  fracture.  Structural  steel, 
before  or  after  heating  to  a  light  cherry  red  heat  and  quenching  in  cold  water,  must 
stand  bending  180°,  to  a  curve  whose  diameter  does  not  exceed  the  thickness  of  the 
sample,  without  signs  of  fracture. 

The  finished  bars,  plates  and  shapes  must  be  free  from  all  cracks,  flaws,  seams, 
blisters  and  other  defects;  must  have  a  smooth  surface  and  be  well  straightened  at 
the  mill  before  shipment. 

The  tensile  strength,  limit  of  elasticity  and  ductility  should  be  determined  from 
standard  test  pieces,  cut  from  the  finished  material,  of  at  least  one-half  square  inch 
sectional  area,  two  opposite  sides  of  the  test  piece  shall  be  the  rolled  surface,  the  other 
two  opposite  surfaces  to  be  milled  or  planed  parallel;  rivet  rounds,  however,  must  be 
tested  of  the  full  size,  as  rolled.  All  test  pieces  should  show  a  fracture  of  a  uniform, 
fine  grained,  silky  appearance,  of  a  bluish  gray  or  "dove"  color,  and  should  be  entirely 
free  from  granular,  brilliant  and  black  specks  of  a  fiery  luster. 

Every  finished  piece  of  steel  should  be  clearly  stamped  with  the  melt  numbers. 

The  inspection  of  the  steel,  to  insure  its  compliance  with  the  specifications,  neces- 
sarily takes  place  at  the  mill,  and  it  is  common  to  introduce  a  clause  in  the  specifica- 
tions by  which  any  material  accepted  at  the  mill,  which,  in  the  process  of  manufacture, 
while  under  the  punches  or  shears,  shows  that  it  is  not  of  uniform  quality,  may  be 
rejected  at  the  shops. 

In  some  cases  a  drifting  test  is  called  for,  by  which  a  hole  punched  in  a  plate  or 
piece,  the  thickness  of  the  material  in  some  cases  being  specified,  can  be  drifted  to  a 
larger  diameter,  without  cracking  either  the  edges  of  the  hole  or  the  external  edge  of 
the  piece,  the  increase  in  the  diameter  of  the  hole  ranging  from  one-third  to  one-half 
the  original  diameter.  The  distance  from  the  center  of  the  hole  to  the  edge  of  the 
piece  may  also  be  specified. 

ARCHITECTURAL  FEATURES. 

Review.  —  Rapid  progress  has  been  made  in  the  general  design  of  central  sta- 
tions by  the  architect  as  well  as  by  the  engineer.  This,  of  course,  varies  in  differ- 
ent countries,  some  laying  much  stress  upon  the  artistic  appearance,  while  others 
confine  attention  solely  to  utilitarian  objects,  disregarding  entirely  the  general  archi- 
tectural features,  as  well  as  the  pleasing  appearance  of  the  general  layout.  The 
conditions  in  these  respects  are  characteristic  of  the  different  countries. 

An  ornamental  building  will  not  increase  the  operating  efficiency  of  the  machinery, 
while  it  may  increase  the  fixed  charges,  but  at  the  same  time  it  is  highly  desirable, 


7° 


STEAM-ELECTRIC    POWER    PLANTS. 


B*HJ®tP0r~1W — iff-  •V^BO®1 — W — "W — ^|P 


FIG.  i.     Fagade  of  the  Grove  Road  Plant,  London,  showing  one-third  of  the  plant.     By 
Courtesy  of  Mr.  C.  Stanley  Peach,  London. 


ARCHITECTURAL    FEATURES.  71 

from  an  ethical  point  of  view,  that  the  shell  encasing  a  power  plant  should  be  of  some 
appropriate  design.  To  a  certain  extent  it  is  desirable  that  the  building  and  its  sur- 
roundings should  present  a  pleasing  appearance,  and  there  is  no  doubt  that  such  sur- 
roundings have  a  certain  effect  on  the  morale  of  the  operating  force  which  conduces 
to  its  increased  efficiency. 

The  ultimate  and  only  aim  sought  for  is  to  deliver  power  to  the  transmission 
lines  at  the  lowest  cost,  and  the  building  with  its  contained  machinery  is  but  a  com- 
pleted machine  for  this  purpose.  The  steel  frame  and  the  architecture  of  the  build- 
ing must  be  adapted  to  the  purpose  to  be  served.  There  are  a  number  of  expensive 


FIG.  2.     Fa9ade  of  Waterside  Plant  No.  2,  New  York  (Electrical  World}. 

power  plants,  particularly  in  the  United  States,  which  present  evidence  of  lack  of 
co-operation  between  the  engineer  and  the  architect. 

In  the  past  few  years  much  more  attention  has  been  paid  in  America  and  Great 
Britain  to  the  artistic  design  of  electric  generating  stations,  the  architectural  appear- 


72  STEAM-ELECTRIC    POWER    PLANTS. 

ance  of  such  plants  not  having  had  the  importance  that  from  the  beginning  has  pre- 
vailed in  continental  Europe. 

It  is  a  remarkable  fact  that  the  plants  in  continental  Europe  which  stand  out  promi- 
nently with  respect  to  architectural  features  and  pleasing  interior  are  also  the  most 
economical  in  operation.  This  close  association  of  art  and  engineering  science  is  only 
characteristic  of  Europe,  and  if  one  takes  into  consideration  the  great  progress  there 
made  in  the  reduction  of  fuel  consumption  to  produce  a  horse-power  hour  (for  ex- 
ample, many  plants  operate  with  a  steam  consumption  as  low  as  10  to  9  pounds  per 
horse-power  hour)  one  will  realize  that  engineering  design  has  not  been  sacrificed  to 
architectural  effect.  Although  the  continental  engineer  may  consider  that  he  has 
artistic  taste,  he  seldom  undertakes  alone  the  laying  out  of  the  entire  plant,  but  is  in 
close  touch  with  the  designers  of  the  architectural  staff.  Under  these  conditions  it  is 
easily  possible  to  create  a  structure  pleasing  to  look  upon. 

In  the  United  States  and  Great  Britain  the  general  practice  is  to  give  out  the  contract 
for  the  designing  of  the  plant  to  a  firm  of  consulting  engineers,  or  where  the  plant  is 
that  of  a  traction  or  railroad  company  an  engineering  force  is  engaged  and  the  entire 
plant  is  designed  in  their  office,  in  some  cases  without  the  slightest  architectural  assist- 
ance. A  few  exceptions,  however,  are  noticeable  in  which  engineering  and  archi- 
tectural talent  have  been  combined  to  secure  harmonious  results.  A  case  in  point 
is  the  Port  Morris  plant  of  the  New  York  Central  Railroad,  in  which  the  coal  tower 
has  been  architecturally  treated  in  a  manner  to  harmonize  with  the  main  structure,  also 
the  New  York  Subway  power  house. 

One  of  the  prominent  European  plants  is  the  twin  municipal  station  of  the  City  of 
Vienna.  This  plant  is  located  in  the  suburbs  and  is  surrounded  by  grass  plots  in  which 
trees  have  been  set  out.  The  grounds  are  surrounded  by  a  picket  fence.  The  two  main 
buildings,  as  well  as  the  auxiliary  buildings  with  their  many  towers  and  cornices,  are 
of  medieval  appearance,  typical  of  the  fourteenth  century.  This  style  of  architecture 
is  much  favored  on  the  Continent.  The  two  main  buildings  are  well  situated  and  are 
symmetrical  in  every  respect,  there  being  two  tall,  ornamental  chimneys  for  each. 

Another  architecturally  beautiful  plant  is  that  of  the  City  of  Hanover,  Germany. 
This  plant  is  also  located  in  the  suburbs,  nevertheless  its  architectural  features  are 
developed  to  the  smallest  detail,  and  the  general  appearance  of  the  plant  is  such  as  not 
to  present  a  huge  building,  although  the  generating  room  at  the  left  is  of  great  height. 
This  room  is  provided  with  wide,  prominent  arched  windows  with  diamond-shaped 
panes,  thus  relieving  its  appearance  of  height.  A  large  window  area  is  provided  on 
the  side  of  the  generating  room,  insuring  good  light.  Creditable  as  the  design 
of  the  station  is,  a  discord  is  struck  by  the  old  wooden  fence  that  still  surrounds  the 
building,  and  a  large  and  unsightly  water-cooling  tower  at  the  right  could  probably 
have  been  made  to  match  the  building,  provided  it  had  been  built  of  steel  or  reinforced 
concrete  instead  of  wood.  Such  inconsistent  features,  although  they  detract  from  the 
appearance  of  the  plant,  are  frequently  found  in  otherwise  finely  designed  continental 
plants,  probably  due  to  the  fact  that  the  architect  was  not  consulted  in  connection 
with  these  additional  features. 


ARCHITECTURAL    FEATURES. 


73 


74 


STEAM-ELECTRIC    POWER    PLANTS. 


One  of  the  most  remarkable  power  plant  structures  architecturally  considered  is 
that  at  Dresden  of  the  plant  for  heating  and  lighting  the  royal  and  municipal  build- 
ings of  the  capital  of  Saxony.  The  territory  to  be  supplied  includes  the  fine  residence 


FIG.    4.      High-Pressure  Steam  Heating  Central  and  Lighting  Plant  at  Dresden, 

Germany. 

district  of  the  city,  extending  along  the  banks  of  the  Elbe,  and  as  the  only  available  situ- 
ation for  the  power  house  was  in  the  rear  of  the  Royal  Theater  near  the  river,  it  was 
necessary  for  the  structure  to  harmonize  with  the  surrounding  buildings.  A  medieval 


ARCHITECTURAL    FEATURES. 


75 


style  of  architecture  was  adopted.  The  building  is  constructed  of  rough-faced  granite 
coursed  ashlar,  with  handsome  pavilions  at  the  corners;  the  chimney,  arising  from  the 
center  of  the  building,  is  concealed  within  a  tower  with  a  spiral  staircase  and  heavy 
ornamental  stone  trimming.  The  entire  plant  is  remarkable  for  its  fitness  to  its  sur- 
roundings, while  typifying  its  purpose. 

A  handsome  and  imposing  structure  is  that  of  the  New  York  Rapid  Transit  Subway 
on  West  59th  Street.  This  structure  faces  properly  on  nth  Avenue  and  this  facade 
is  most  elaborately  treated,  and  the  ornamental  scheme  is  also  carried  along  the  north 
and  south  fronts.  The  general  style  of  the  building  is  what  may  be  called  French 
Renaissance,  and  the  color  scheme  has  therefore  been  made  rather  light  in  character. 
The  base  of  the  exterior  walls  has  been  finished  in  cut  granite  up  to  the  water  table, 
above  which  the  walls  are  faced  with  light  buff  pressed  brick.  This  brick  has  been 
enriched  by  the  use  of  similarly  colored  terra  cotta,  which  appears  in  the  pilasters 
about  the  windows,  in  the  several  entablatures  and  in  the  cornice  and  parapet  work. 

All  window  frames  and  sashes  are  of  uniform  design  and  constructed  of  cast  iron, 
and  all  the  windows  are  glazed  with  wired  glass  for  protection  purposes.  The  sloping 


FIG.  5.     Interior  of  Generating  Room,  L  St.  Plant,  Boston. 

sides  of  the  roofs  are  constructed  with  terra  cotta  blocks  protected  by  waterproofing, 
and   over  this  are  laid  Spanish  roll  tiles  which  are  enameled  a  dark  green  on  the 


76  STEAM-ELECTRIC    POWER    PLANTS. 

exposed  surface.  The  sloping  sides  of  the  roof,  directly  over  the  operating  room,  are 
constructed  of  heavy  glass,  suitably  supported  on  steel  bars  with  copper  trim  work. 
Copper  condensation  gutters  are  provided,  and  under  each  section  of  glass  is  erected 
a  wire  screen. 

The  main  doorways  leading  into  the  structure  are  trimmed  with  cut  granite,  and 
the  entrance  lobby  in  the  northeast  corner  is  finished  with  a  marble  wainscoting.  The 
exposed  wall  of  the  operating  room  is  faced  with  a  light  cream-colored  pressed  brick, 
with  an  enamel  brick  wainscoting  eight  feet  high,  extending  around  the  entire  operating 
area;  the  wainscoting  is  white,  except  for  a  brown  border  at  the  base.  The  office, 
the  toilets  and  locker  rooms  are  finished  and  fitted  with  marble  and  other  materials 
in  harmony  with  the  general  character  of  the  building. 

Two  other  recent  American  central  stations  also  show  a  great  advance  in  power 
plant  architecture,  viz.,  the  Fisk  Street  station  of  the  Commonwealth  Electric  Com- 
pany, Chicago,  111.,  and  that  of  the  Boston  Edison  Illuminating  Company  in  Boston, 
Mass.  In  both  of  these  stations  the  interior  of  the  operating  room  is  finished  with 
enameled  brick;  the  Fisk  Street  station  being  almost  entirely  white,  while  in  Boston 
the  white  tiling  is  set  off  by  green  outlined  panels  between  the  pilasters.  In  these 
stations  the  columns  of  the  steel  frames  are  concealed  by  pilasters,  between  which 
arches  are  sprung  below  the  crane  runway  girders;  the  latter  being  entirely  hidden, 
the  only  steel  work  visible  being  that  in  the  roof  system.  The  room  is  lighted  by  a 
continuous  skylight  in  the  monitor,  giving  a  very  pleasing  general  illumination.  In 
the  Fisk  Street  station  a  visitors'  gallery  has  been  provided  for  the  convenience  of 
sight-seers.  It  would  be  easily  possible  to  give  a  large  number  of  examples  on  this 
subject,  but  the  general  points  to  be  considered  will  now  be  taken  up  and  discussed. 

Windows  and  Doors.  —  The  windows  of  the  side  walls  should  be  to  as  great  an 
extent  as  possible  arranged  symmetrically  with  regard  to  the  spacing  of  the  generator 
units.  It  is  desirable  to  secure  a  large  area  of  window  surface,  and  the  design  should 
be  well  considered.  Arched  tops  give  a  very  handsome  appearance  and  in  some  cases 
diamond-shape  panes  of  glass  have  been  used  to  add  to  the  effect.  The  large  windows 
should  be  paneled  in  a  manner  consistent  with  their  design. 

The  doorways  should  be  ornamental,  massive  and  of  suitable  size,  as  has  been  pre- 
viously mentioned.  Oak,  well  paneled,  makes  a  very  handsome  door,  particularly 
when  trimmed  with  bronze.  In  many  cases,  however,  metallic  doors  are  used,  as  it 
is  desirable  to  avoid  the  naked  appearance  of  the  ordinary  fireproof  shutter. 

Crane.  —  The  crane  may  not  appear  an  architectural  feature,  but  even  this  un- 
promising subject  may  yield  to  suitable  treatment.  It  should  be  designed  to  conform 
in  a  way  to  the  roof  trussing.  In  continental  Europe  lattice  frame  girders  are  often 
used  for  this  purpose,  very  few  plate  or  box  girder  frames  being  employed.  In  America 
and  to  a  certain  extent  in  Great  Britain  the  question  of  first  cost  generally  governs, 
instead  of  artistic  considerations,  and  for  this  reason  the  unsightly  fish-bellied  box 
girder  is  prominently  in  evidence. 


ARCHITECTURAL    FEATURES. 


77 


0> 

I 


vO 

o 


78  STEAM-ELECTRIC    POWER    PLANTS. 

Walls.  —  The  walls,  particularly  those  of  the  operating  room,  should  be  light 
colored,  preferably  faced  with  glazed  brick,  or  cement  plastered  and  with  a  wainscoting 
of  a  contrasting  color.  Pilasters  may  be  used  to  break  up  the  monotony  of  a  smooth 
surface  and  to  conceal  the  steel  columns  if  desirable.  A  very  handsome  appearance 
may  be  secured  by  outlining  the  panels  between  the  pilasters  with  brick  of  another 
color.  The  crane  girders  can  be  concealed  by  a  cornice  supported  with  arches  between 
the  pilasters. 

Floors.  —  From  any  standpoint  a  tile  or  mosaic  floor  is  the  most  desirable, 
being  smooth,  easily  kept  clean  and  having  a  handsome  appearance.  In  addition  it 
is  often  the  practice  on  the  Continent  to  lay  carpeting  in  the  main  passageways.  If 
common  cement  flooring  is  used  it  should  be  granitoid  finish  to  imitate  tiling  and 
well  rubbed  down  to  a  smooth,  even  surface.  The  floor  should  in  this  case  be  of  a 
dark  color  in  order  to  render  drips  of  oil  and  water  inconspicuous. 

Pipe  Trenches.  —  All  piping  where  brought  through  the  floor  should  be  surrounded 
by  cast-iron  thimbles,  preferably  extending  slightly  above  the  floor  level,  as  previously 
stated.  In  the  walls  similar  thimbles  should  be  used,  projecting  about  a  quarter  of  an 
inch  beyond  the  finished  face  of  the  wall.  The  wall  thimbles  should  be  provided  with 
sheet- iron  covers  fitted  to  the  pipe  covering  and  painted  to  harmonize  with  the  general 
appearance  of  the  plant.  The  purpose  of  these  covers  is  to  prevent  dust  and  dirt 
entering  from  the  boiler  room.  Where  large  openings  must  be  made  in  the  floor  for 
big  pipes,  such  as  the  tail  pipes  of  barometric  condensers,  exhaust  piping,  etc.,  it  is 
advisable  to  provide  a  cast-iron  floor  plate  fitting  the  pipe  with  the  thimble,  to  prevent 
dirt  from  falling  through. 

The  piping  should,  as  far  as  possible,  be  kept  out  of  the  generating  room.  This  is 
particularly  necessary  in  vertical  turbine  plants,  if  a  good  appearance  is  to  be  con- 
sidered, but  this  is  difficult  where  no  basement  is  provided,  since  it  is  necessary  to  group 
the  condenser  and  auxiliary  machinery  with  the  main  units.  Such  piping  as  is  used 
should  be  run  with  easy  bends  and  in  as  inconspicuous  a  manner  as  possible. 

Galleries.  —  In  all  plants  a  number  of  galleries  are  required  to  provide  means  of 
communication  and  to  reach  different  parts  of  large  machines.  While  machine  gal- 
leries hardly  come  within  the  province  of  the  architect,  they  should  be  designed  to 
conform  with  the  other  galleries  and  the  railings  throughout  should  be  of  uniform 
height  and  design.  Half  brass,  half  iron  railings,  while  often  used  for  their  supposedly 
artistic  appearance,  are  neither  one  thing  nor  the  other.  Brass  is  not  a  suitable  material 
for  railings;  iron  railings  have  a  more  substantial  appearance  and  can  be  made  as 
handsome  as  may  be  desired.  The  gallery  plates  and  brackets  should  be  uniform,  it 
being  undesirable  to  employ  cast  iron  in  one  place  and  concrete  or  steel  in  another. 
Cast-iron  plates,  their  top  being  finished  in  a  diamond  pattern,  and  having  a  slight 
curve  around  their  outer  edge,  present  a  good  appearance  and  are  eminently  satis- 
factory. 


ARCHITECTURAL    FEATURES. 


79 


80  STEAM-ELECTRIC    POWER    PLANTS. 

Switchboard.  —  In  small  plants  it  is  practicable  to  place  the  switchboard  at  one  end 
of  the  generating  room,  which  is  a  very  favorable  location,  but  in  plants  over  10,000 
horse-power  the  switchboard  becomes  so  large  that  this  location  cannot  be  used,  and 
it  must  be  placed  on  the  side  of  the  room.  The  switchboard  should  be  located  in  a 
gallery  or  in  a  special  lean-to,  facing  the  generator  room.  Frequently  in  smaller  plants 
the  switchboard  structure  forms  the  partition  between  generating  and  switching  rooms. 
The  switchboard  should  preferably  be  of  a  light  color,  principally  on  the  score  of  clean- 
liness, and  should  be  artistically  designed  in  accord  with  the  costly  instruments  upon  it. 
In  a  few  cases  iron  has  been  used  for  the  entire  switchboard,  entailing  considerable 
care  in  insulating.  Usually  slate,  black  granite  or  white  marble  is  preferred  for  this 
purpose.  The  latter  practice  is  common  on  the  Continent,  the  panels  being  framed 
with  dark  toned  ornamental  metal,  and  by  a  symmetrical  arrangement  of  the  different 
instruments  a  highly  pleasing  appearance  may  be  secured.  The  use  of  black  granite 
or  slate  panels,  without  any  ornamental  border,  is  the  everyday  American  practice. 
In  a  few  cases  the  switchboard  has  been  separated  from  the  generating  room  by  glazed 
partitions,  in  other  cases  simple  arched  openings  have  been  employed  with  good  effect. 
It  is  advisable  to  provide  an  extension  of  the  gallery  into  the  generating  room,  as  a 
pulpit  from  which  the  operator  can  see  all  parts  of  the  plant.  A  very  handsome  switch- 
board, artistically  arranged,  is  that  of  the  Charlottenburg  plant.  The  switchboard 
here  stands  on  a  gallery  recess  in  the  end  wall  of  the  building,  which  is  carried  across 
the  front  of  the  gallery  with  arched  openings  and  columns  above  the  pilasters.  The 
switchboard  is  of  white  marble  set  in  a  dark  framing.  The  operator  overlooks  the  gen- 
erating room,  of  which  every  point  is  visible.  The  roof  construction  is  designed  in 
harmony  with  the  appearance  of  the  entire  pfent,  while  the  floor  is  finished  with 
mosaic  tiling  in  a  manner  common  in  continental  power  houses. 

Boiler  Room.  —  The  boiler  room  has  not  received  much  attention  from  the  archi- 
tect, it  being  considered  of  less  importance.  In  continental  Europe  one-story  boiler 
rooms  are  the  rule,  and  for  these  it  is  possible  to  secure  a  better  appearance  than  is 
practicable  with  the  multi-storied  boiler  rooms  used  in  America  and  Great  Britain. 
The  former  rooms  can  be  lighted  by  overhead  skylights,  and  where  the  boiler  settings 
are  faced  with  white  enamel  brick  a  very  light  appearance  is  possible,  in  the  absence 
of  overhead  bunkers.  By  dividing  the  bunker  construction  so  as  to  permit  a  central 
skylight,  it  is  possible  to  secure  a  very  good  boiler  room,  and  this  arrangement  has 
been  adopted  in  some  places. 

The  unsightliness  of  most  boiler  rooms  arises  from  the  fact  that  no  provisions  are 
made  to  keep  them  clean,  and  cleanliness  is  not  insisted  upon.  Coal  should  not  be 
allowed  in  heaps  before  the  fire  doors,  and  ashes  should  be  removed  frpm  the  pit  and 
not  left  in  piles  on  the  floor,  as  is  often  the  case.  Racks  or  hooks  should  be  provided 
for  the  firing  irons  and  tools,  and  their  use  should  be  insisted  upon,  no  tools  being  per- 
mitted to  lie  about  the  floor  or  lean  against  the  walls.  The  pipe  covering  should  be 
painted  a  uniform  color  and  smoothly  finished,  so  that  it  can  be  kept  free  from  dust 
and  dirt.  Suitable  uniform  galleries  and  walkways  should  be  provided  by  which  all 


ARCHITECTURAL    FEATURES. 


8l 


FIG.  8.     Interior  of  Boiler  Room,  Municipal  Plant,  Frankfurt  on  the  Main,  Germany. 


82  STEAM-ELECTRIC    POWER    PLANTS. 

points  can  be  easily  reached.  The  walls  should  be  whitewashed  or  finished  in  some 
light  color  and  should  be  kept  clean.  It  may  seem  impracticable  to  insist  on 
spotless  cleanliness  in  a  room  where  coal  dust  is  continually  blowing  around,  but  it  is 
not  impossible. 

Removal  of  Ashes.  —  A  portion  of  the  boiler-room  basement  below  the  boilers  or 
firing  aisle,  in  plants  where  a  basement  is  built,  is  usually  reserved  for  the  handling 
of  ashes,  soot  and  dirt  from  the  boilers,  provision  being  made  for  conveying  it  to  storage 
bins  for  shipment.  In  some  plants  this  is  done  by  means  of  a  conveyor  underneath  the 
ash  hoppers,  in  others  ash  cars  of  about  one-ton  capacity  running  on  an  industrial 
track  operated  by  hand  labor  or  by  a  small  electric  locomotive.  As  these  ashes  are 
wet  down  in  the  ash  hopper  to  quench  them,  it  is  necessary  to  provide  a  suitable  gutter, 
immediately  beneath  the  ash  spouts,  for  conveying  this  water  to  the  drainage  system. 
The  basement  should  not  be  used  as  a  storage  room  for  ashes.  The  conveyors  beneath 
the  boiler  floors  or  the  ash  cars  discharge  into  a  hopper,  from  which  the  ashes  are 
taken  to  the  storage  bin,  and  it  is  necessary  to  the  efficient  operation  and  the  appear- 
ance of  the  plant  that  these  ashes  should  be  entirely  removed,  and  the  portion  of  the 
plant  reserved  for  handling  them  should  be  kept  clean. 

The  main  ash  hopper  is  preferably  located  adjacent  to  the  point  at  which  coal  is 
received,  either  inside  of  the  building  or  outside,  in  order  that  the  empty  coal  cars  may 
be  utilized  for  the  removal  of  ashes  without  shifting. 

Coal  Storage  Plant,  --  The  coal  tower,  while  a  very  necessary  portion  of  the  plant, 
is  badly  neglected  from  an  architectural  point  of  view.  Although  it  is  unnecessary  to 
attempt  any  elaborate  treatment  of  this  part  of  the  plant,  which  would  be  an  exceed- 
ingly difficult  matter  in  many  cases,  particularly  with  traveling  towers,  the  coal  tower 
as  usually  designed  is  a  steel  structure,  and  should  match  the  building,  bearing  in  mind 
its  purpose.  Too  often  this  tower  is  rendered  very  unsightly  by  a  rough  corrugated 
iron  or  wooden  plank  sheathing.  An  excellent  example  of  the  architectural  possibili- 
ties in  the  design  of  a  coal  tower  is  presented  by  the  Vienna  twin  municipal  plant  and 
by  the  two  plants  of  the  New  York  Central  Railroad  Co.,  one  located  at  Yonkers  and 
the  other  at  Port  Morris,  in  the  vicinity  of  New  York  City,  where  the  coal  tower  has 
been  designed  practically  as  a  portion  of  the  main  building.  In  some  cases,  however, 
the  type  of  the  coal  tower  and  ash  bunkers  is  governed  by  local  conditions  and  the 
system  of  conveyors  installed,  so  that  it  is  difficult  to  treat  them  in  a  manner  consistent 
with  the  main  structure. 

In  some  of  the  smaller  plants,  especially  in  Europe,  coal  is  stored  in  a  building 
similar  to  the  main  structure,  or  built  in  the  main  structure  as  a  separate  room,  while 
in  the  large  plants  open  or  exposed  coal  yards  are  sometimes  used,  owing  to  the  large 
quantity  of  fuel  which  it  is  desired  to  carry  in  stock;  but  as  open  coal  storage  plants  do 
not  lend  themselves  to  architectural  treatment,  it  is  hardly  possible  to  do  anything  with 
an  exposed  plant  except  to  keep  the  coal  piled  in  fairly  good  shape,  which  is  a  matter 
in  the  hands  of  the  operating  executive. 


ARCHITECTURAL    FEATURES. 


Chimneys.  —  One  of  the  most  important  parts  of  a  plant,  and  a  feature  much 
neglected  architecturally,  is  the  chimney.  In  many  plants  these  are  of  such  over- 
powering size  that  the  main  building  appears  as  merely  a  pedestal  for  the  shaft.  In 
many  cases  these  chimneys  do  not  in  any  way 
harmonize  with  the  appearance  of  the  building 
or  its  construction,  the  finish  of  the  chimney 
shaft  being  of  such  a  radically  different  design 
from  that  of  the  building  that  it  reacts  upon 
this  in  a  detrimental  manner.  A  large  plant 
with  one  or  two  massive  chimneys  requires 
very  different  treatment  from  a  building  in 
which  a  number  of  smaller  stacks  are  erected. 
The  chimneys  have  such  an  effect  on  the  ap- 
pearance of  the  building  that  it  will  be  desirable 
to  arrange  the  window  and  roof  construction  in 
accord  with  them. 

Conclusion.  —  Too  much  attention  cannot 
be  called  to  the  fact  that  in  the  design  of  a 
power  house  the  whole  structure  must  be 
considered  together  with  its  surroundings  to 
secure  a  pleasing  appearance.  Frequently  the 
case  arises  that  the  plant  is  located  in  a  neigh- 
borhood where  the  character  of  the  surrounding 
structures  may  entirely  govern  the  architectural 
features  of  the  plant,  it  being  desirable  to  secure 
a  well-designed  plant,  and  without  any  appear- 
ance of  clumsiness.  For  this  reason  multi-story 
boiler  plants  with  a  parallel  generating  room  of 
equal  height  are  difficult  to  treat  from  an  archi- 
tectural point  of  view.  A  lower  building,  in 
which  offsets  can  be  made  and  the  height  of 
the  structure  varied  to  suit  the  different  por- 
tions of  the  plant,  offers  a  much  better  oppor- 
tunity for  the  architect  to  display  his  skill  and 
ability. 

It  cannot  be  expected  that  every  plant 
should  be  architecturally  treated  in  the  same 
manner  as  the  Hanover  plant,  or  to  secure 
the  Gothic  appearance  of  the  interior  of  the 
Charlottenburg  plant,  and  in  a  way  such 

structures  are  undesirable  on  account  of  the  expense  entailed  in  construction,  but  it 
must  always  be  remembered  that  a   pleasing    appearance    can    always    be    secured 


FIG.  9.  Chimney  of  the  Electric 
Power  Plant  in  Munich  (from  a 
sketch,  and  by  courtesy  of  Mr.  C. 
Stanley  Peach,  London}. 


84  STEAM-ELECTRIC    POWER    PLANTS. 

without  any  additional  expense.  In  fact  many  of  the  prominent  plants  which  are 
notorious  for  ugliness  have  cost  more  for  building  than  those  which  are  noted  for  their 
fine  appearance,  a  proper  knowledge  of  architectural  conditions  being  requisite  to 
secure  such  results,  which  cannot  be  obtained  by  the  strictly  mechanical  engineer. 

In  this  present  age  of  art  and  science,  when  engineering  and  architecture  stand  so 
high,  it  is  peculiarily  unfortunate  that  every  year  such  a  number  of  unattractive  struc- 
tures are  created  for  the  production  of  power,  and  that  a  greater  part  of  the  power 
plants  in  America  and  Great  Britain  are  masterpieces  of  ugliness.  The  prime  requisite 
in  the  architectural  feature  of  these  structures  is  that  the  design  must  be  well  con- 
sidered in  all  points  from  foundation  to  chimney  top,  and  the  building  should  be  typical 
of  its  purpose,  viz.,  as  that  of  a  power  plant. 


CHAPTER    IV. 
BOILERS. 

Type  of  Boiler.  —  The  conditions  governing  the  design  of  a  boiler  are  of  such  a 
varying  nature  that  it  may  be  stated  as  a  general  truth  that  no  standard  boiler  is  the 
most  efficient  for  the  combination  of  circumstances  other  than  the  particular  circum- 
stances for  which  this  standard  boiler  was  designed.  The  first  question  to  be  decided 


FIG.  i.     Interior  of  Boiler  Room,  "  Bille  "  Plant,  Hamburg. 

in  the  choosing  of  a  boiler  is  the  type  of  boiler  to  be  suited  to  the  conditions.  In  general 
we  may  say  that  the  type  is  practically  determined  by  the  character  of  the  load  which 
the  boiler  has  to  carry.  That  is,  for  instance,  in  the  case  of  a  railroad  power  plant, 
where  the  load  undergoes  rapid  fluctuations,  the  water-tube  type  will  be  found 

85 


86  STEAM-ELECTRIC    POWER    PLANTS. 

to  fill  the  conditions  best,  on  account  of  the  fact  that  it  carries  only  a  comparatively 
small  amount  of  water,  and  hence  is  better  adapted  for  rapid  steaming.  However,  it 
must  be  borne  in  mind  that  a  readily  available  supply  of  heated  water  is  essential  to 
the  economical  operation  of  this  type  of  boiler.  On  the  other  hand,  where  the  requisite 
supply  of  heated  water  is  not  available,  the  shell  boiler  will  better  meet  the  conditions 
imposed,  on  account  of  the  fact  that  it  has  a  large  storage  capacity.  The  space  available 
for  boilers  may  have  considerable  bearing  on  the  choice  of  the  type,  hence  is  an  impor- 
tant point  for  consideration,  especially  in  the  equipment  of  existing  plants  with  new 
boilers.  For  instance,  plenty  of  vertical  space  may  be  available  whereas  the  floor 
space  is  limited,  therefore  the  upright  type  of  boiler  may  be  found  best  suited  to  the 
conditions. 

The  volume  of  water  contained  in  the  water-tube  boilers,  as  has  been  stated,  is  less 
than  that  contained  in  the  fire-tube  boilers.  This,  of  course,  is  a  slight  advantage  in 
favor  of  the  fire-tube  boilers,  since  the  greater  volume  of  water  affords  a  means  for 
storing  superfluous  heat  at  times  when  it  is  not  required  for  making  steam.  This 
advantage,  however,  is  greatly  outweighed  by  those  already  shown  in  favor  of  the  water- 
tube  boilers.  For  this  reason  the  water-tube  boiler  has  been  adopted  for  practically 
all  modern,  and  especially  large  power  plants.  There  are  quite  a  number  of  plants 
in  which  the  fire-tube  boiler  is  used  to  advantage.  These  plants  are  practically  all 
operated  on  comparatively  low  steam  pressures,  say  up  to  1 50  or  160  pounds.  Water- 
tube  boilers  are,  however,  run  on  a  pressure  of  200  to  250  pounds  per  square  inch, 
or  even  higher,  as  are  also  some  shell  boilers.  An  example  of  the  use  of  very 
high  pressure  water-tube  boilers  was  to  be  seen  at  the  St.  Louis  Exposition,  1904. 
In  this  instance  a  Delaunay  Belleville  boiler  furnished  steam  at  a  pressure  ranging 
from  295  to  310  pounds,  to  a  six-cylinder  quadruple  expansion  engine  of  the  same 
manufacture.  This  boiler  contained  a  superheater  which  raised  the  temperature  of 
the  steam  to  750°  Fahr.  While  the  above-mentioned  instance  of  high  pressure  boiler 
was  intended  primarily  for  exhibition  purposes,  the  writer  is  of  the  opinion  that  the 
rapidly  increasing  steam  pressures  will  soon  reach  from  225  and  higher  for  everyday 
practical  use.  The  use  of  steam  at  200  pounds  per  square  inch  is  common  practice 
today  in  modern  plants  in  Europe,  another  instance  of  which  is  to  be  had  in  the 
Long  Island  City  power  plant  of  the  Pennsylvania  Railroad. 

Safety.  — The  question  of  safety  is  one  of  the  most  essential  requirements  which 
the  designer,  constructor  and  user  of  steam  boilers  must  consider.  As  can  be  readily 
understood  the  quantity  of  stored  heat  energy  in  a  steam  boiler  is  usually  enormous, 
and  if  set  free  by  the  rupture  of  the  containing  vessel  widespread  disaster  will  gen- 
erally ensue.  The  damage  ordinarily  wrought  in  such  cases  covers,  not  only  the 
destruction  of  property,  but  is  almost  always  accompanied  by  loss  of  life. 

To  secure  a  boiler  which  is  safe  the  best  material  and  workmanship  must 
be  employed  throughout.  The  material  needed  for  the  purpose  should  be  as  strong, 
tough  and  ductile  as  it  can  possibly  be  made.  Of  these  qualities  that  of  ductility  is 
perhaps  the  most  important,  since  this  gives  the  material  its  capability  of  being  altered 


BOILERS. 


in  form  without  fracture.     A  lack  of  tenacity,  for  instance,  can  be  met  by  making  the 
material  thicker,  but  if  brittle  the  material  will  rupture  with  abrupt  changes  of  form, 


BUCK  STAV 


%»»!.. 


f= 


^  L?  6  x6*x  Vj," 


TOP  CQ». 

SOT.    •• 


/l'  PUn.    I.C.N4TH 


I¥-0"A&OVB  BASEMENT 


FIG.  2.     Steel  Work  and  Boiler  Setting  of  two  604  H.P.  Babcock  and  Wilcox  Boilers. 


however  thick  it  may  be  made.     The  best  boiler  plate  must  possess  great  strength  and 
must  combine  with  this  a  great  ductility.     High  elasticity  of  material  must  also  be  had. 


88  STEAM-ELECTRIC    POWER    PLANTS. 

Cast  iron  should  never  be  employed  for  principal  parts  of  a  steam  boiler,  nor  should 
any  trust  be  placed  in  so-called  semi-steel  or  "steel  alloy." 

The  general  construction  of  the  boiler  should  be  such  that  all  parts  are  readily 
accessible  for  cleaning  purposes,  inspection  and  repairs  in  case  of  leaks  or  accidents. 
In  the  general  design  of  water-tube  boilers  the  small  unit  principle  employed  in  the 
making  up  of  the  heating  surface  precludes  the  idea  of  immediate  personal  access 
to  the  inside  of  the  tubes  for  cleaning  and  inspection.  Tubes  or  units  of  such  a  form 
that  they  cannot  be  inspected  inside  over  their  entire  length,  or  which  are  so  curved 
that  they  cannot  be  properly  cleaned  by  scrapers  or  cleaners,  are  claimed,  by  some 
authorities,  to  be  objectionable.  Some  types  of  boilers  embodying  such  features  have 
other  advantages  which  may  outweigh  the  disadvantage  due  to  curved  tubes. 

Simplicity.  — The  boiler  to  be  adopted  should  have  as  few  joints  as  possible,  be 
of  as  simple  design  as  can  be  made  use  of,  as  the  more  joints  there  are  and  the  more 
complicated  the  design  the  greater  will  be  the  trouble  in  making  repairs,  and  keeping 
these  tight.  Joints  between  tubes  and  headers,  and  tubes  and  drums  are,  for  the 
most  part,  made  by  expanding  the  tubes.  In  some  types  of  boilers  hand  holes  with 
additional  ground  joint  caps  are  required  to  give  access  to  the  tubes.  The  principal 
objection  to  the  cap  feature  in  boilers  of  this  type  is  the  multiplication  of  joints,  which 
are  sometimes  an  occasion  for  leakage  and  corrosion.  Unless  properly  attended  to 
these  ground  joints,  when  once  they  begin  to  leak,  are  soon  cut  by  the  action  of 
the  passing  water,  and  in  many  instances  have  to  be  refaced.  This  is  troublesome, 
requires  time,  and  unless  a  large  supply  of  duplicate  caps  is  kept  on  hand  may  cause 
the  closing  down  of  the  boiler. 

Durability.  —  The  construction  of  any  boiler  should  be  such  that  an  even  tem- 
perature may  be  readily  maintained  throughout  the  furnace  and  flues.  Tubes  or 
other  parts,  when  exposed  to  varying  temperatures,  are  liable  to  be  cracked  or  strained 
by  the  uneven  expansion,  and  the  maintenance  of  an  even  temperature  is  also  con- 
ducive to  economical  evaporation.  Besides  provisions  for  maintaining  the  tempera- 
ture of  the  gases,  it  is  essential  that  there  be  rapid  and  uniform  circulation  of  the 
water  in  order  to  equalize  the  temperature  within  the  boiler. 

Water  Circulation. — The  circulation  of  water  in  a  boiler  is  caused  by  a  difference 
in  temperature.  Hot  water,  being  lighter,  rises  and  as  it  cools  it  falls  to  the  lowest 
point,  where  it  is  reheated.  It  will,  therefore,  be  seen  that  the  smaller  the  amount  of 
water  per  square  foot  of  heating  surface  the  more  rapid  the  circulation. 

Adequate  means  should  be  provided  for  the  removal  of  steam  as  quickly  as  formed. 
If  steam  pockets,  that  is,  formation  of  steam  completely  filling  a  section  of  the  tube 
exist,  burning  and  blistering  will  result.  Ample  steam  space  should  be  provided,  a 
reservoir  sufficiently  large  to  deliver  the  required  amount  of  steam,  without  variation 
in  pressure,  is  especially  a  requisite  in  water- tube  boilers. 

Heating  Surface.  —  The  heating  surface  of  a  water-tube  boiler,  made  up  of  water- 
surrounded  surfaces,  is,  approximately  ten  square  feet  per  boiler  horse-power,  that  is, 


BOILERS. 


89 


allowing  an  evaporation  of  three  pounds  of  water  per  square  foot.     The  gases  should 
have  a  free  and  unobstructed  passage,  and  should  travel  with  a  uniform  velocity  over 


FIG.  3.  Hornsby's  Horizontal  Boiler  with  McPhail  and  Simpson's  Superheater  as 
installed  in  Bow  Road  Plant,  London.  Note  the  two  firing  places,  at  the  front  and  at  the 
side,  the  latter  is  called  upon  for  sudden  overload.  Heating  surface  of  Boiler  81,000  sq. 
ft.  Superheater  874  sq.ft.  Grate  area  125  sq.  ft. 

the  entire  water  surface  at  a  rate  not  too  great,  but  to  allow  a  complete  absorption  of 
heat  by  the  water. 

Grate  Surface.  —  The  grate  surface  should  be  proportioned  with  regard  to  the 
kind  of  coal  to  be  burned.  With  coal  of  low  heating  value  a  larger  grate  surface  is 
required.  If  the  boiler  setting  will  not  allow  enlargement  it  is  then  necessary  to  attach 
an  extended  furnace,  or  "Dutch  oven."  By  doing  so  the  length  of  the  furnace  will  be 
increased,  so  that  it  is  difficult  to  fire  by  hand,  and  it  is  usual,  therefore,  to  use  a 
mechanical  stoker;  the  latter  will  be  treated  under  a  separate  chapter. 

To  collect  and  remove  soot  and  ashes  conveniently,  hoppers  should  be  installed, 
provided  that  the  boiler  room  contains  a  basement.  The  soot  hoppers  may  be  located 
directly  in  rear  of  the  fire  bridge,  as  shown  in  Fig.  10,  and  should  be  made  of  wrought 
or  cast  iron.  The  latter  may  be  advantageously  used,  as  the  hopper  is  small.  The 
ash  hopper  should  extend  the  entire  width  of  the  boilers,  so  that  the  ashes  will  collect 
without  the  use  of  a  hoe.  It  should  be  large  enough  to  contain  sufficient  ashes  to 
obviate  frequent  removals. 


90  STEAM-ELECTRIC    POWER    PLANTS. 

The  ash  hopper  should  be  constructed  of  iron  or  steel  plates.  Each  hopper  should 
have  two  or  three  gates,  depending  upon  the  size  of  the  boiler.  These  gates  should 
be  large  enough,  about  18  inches  square,  to  prevent  clogging  of  ashes  and  the  use  of 
a  bar  to  break  them  up. 

In  order  to  lengthen  their  life,  the  hoppers  should  be  lined  with  fireproof  tile. 
Hoppers  should  not  be  lined  with  concrete,  for  this  will  crack,  through  the  action  of 
the  hot  ashes,  and  as  these  are  frequently  wetted,  water  will  run  through  the  cracks 
and  settle  between  the  concrete  and  the  iron;  this  will  corrode  the  iron  a  great  deal 
more  quickly  than  if  there  was  no  lining.  Besides,  the  frequent  heating  of  the  concrete 
to  a  high  temperature  will  cause  its  destruction.  A  better  method  is  to  do  away  with 
all  iron  and  construct  a  masonry  hopper,  both  for  soot  and  ashes.  An  example  of 
this  design  is  shown  with  the  description  of  the  Vienna  light  and  power  plants. 

In  smaller  plants  the  hoppers  may  dump  directly  into  a  trench  in  which  there  is  a 
screw  or  chain  conveyor. 


FIG.  4.  Hornby's  "  Upright  "  Boiler  as  installed  in  Bow  Road  Plant  of  the  Charing  Cross 
and  City  Elec.  Co.  of  London.  Heating  surface  per  boiler  10,850  sq.  ft.  McPhail  and 
Simpson's  Superheater  1,036  sq.  ft.  Grate  area  168  sq.  ft.  Normal  evaporation  per 
boiler  33,000  Ibs.  per  hour.  A  battery  as  shown  in  the  Illustration  is  capable  of  evapo- 
rating 100,000  Ibs.  of  water  per  hour. 

Efficiency.  —  A  boiler  should  be  so  designed  that  the  greatest  efficiency  will  be 
obtained  at  normal  load,  but  if  it  is  necessary  to  force  the  boiler  the  efficiency  should 
not  go  far  below  normal.  The  average  efficiency  of  a  boiler  is  from  70  per  cent  to 
72  per  cent,  although  at  times  it  will  run  as  hi~h  as  80  per  cent. 


BOILERS.  9r 

Setting.  —  Modern  practice  is  to  suspend  certain  types  of  water-tube  boilers  so 
that  expansion  may  be  free  and  unobstructed.  After  the  boiler  is  set  up,  the  brick- 
work is  erected.  To  secure  a  satisfactory  service  it  is  necessary  that  the  setting  be 
constructed  with  the  utmost  care  and  best  material,  and  after  setting  is  complete  it 
should  be  thoroughly  dried  before  fire  is  placed  under  boiler. 

Hard  burned  brick  should  be  used  for  the  general  setting.  The  bond  should  be 
as  perfect  as  possible  to  prevent  any  air  leakage.  All  walls  exposed  to  the  action  of 
hot  gases  should  be  lined  with  fire  brick,  bonded  with  fire  clay;  the  fire  clay  mixed 
thin  and  the  joints  between  bricks  be  made  as  narrow  as  possible.  All  doors  should 
be  as  air-tight  as  is  possible.  The  ends  of  the  drums  may  be  covered  with  a  non- 


FIG.  5.     293  H.  P.  Babcock  and  Wilcox  Boiler  with  Superheater  and  Chain  Grate  Stokers, 

conducting  covering,  held  in  place  with  a  wire  netting  over  which  is  placed  a  coat  of 
hard  finish   plaster. 

A  recent  practice  has  been  introduced,  both  in  Great  Britain  and  America,  of 
setting  the  whole  boiler  in  a  steel  casing  which  is  lined  with  fire  brick.  A  notable 
instance  of  this  is  the  Bow  Road  station,  in  which  boilers  of  10,850  square  feet  heating 
surface  are  used.  Another  recent  practice  is  to  provide  a  setting  embodying  a 


92  STEAM-ELECTRIC    POWER    PLANTS. 

double    furnace,  one  at    each   end  of   the  boiler,    which    practice    has    also    been 
adopted  at  the  59th  St.  plant,  New  York,  in  connection  with  several  boilers. 

Boiler  walls  in  large  power  plants  are  usually  carried  on  the  steel  work  of  the  build- 
ing, as  there  is  a  basement  under  the  entire  operating  floor.  An  example  of  this  is 
given  in  the  accompanying  illustration,  Fig.  2,  representing  the  steel  work  and  brick 
setting  for  two  604  horse-power  Babcock  &  Wilcox  boilers,  as  installed  for  the  Potomac 
Electric  Power  Company,  Washington,  D.C. 

Trimmings.  —  It  is  necessary  to  provide  boilers  with  the  usual  fittings,  such  as  safety 
valves,  water  columns,  gauges,  etc.  Safety  valves  may  be  provided  with  a  muffler 
if  the  valves  discharge  directly  into  the  boiler  room,  but  if  the  steam  is  discharged 
to  the  roof,  the  mufflers  may  be  dispensed  with.  The  steam  gauges  should  be  so  located 
that  they  can  be  easily  read  from  the  floor.  Where  large  boilers  are  used  the  gauges 
may  be  located  7  feet  or  8  feet  above  the  floor,  or  else  an  electric  light  provided. 

As  has  already  been  covered  in  the  chapter  on  general  layout,  if  the  boiler  is  of  a 
large  size  it  is  good  practice  to  install  a  gallery  in  front  of  it  for  convenience  in  opera- 
tion, inspection  and  repairs. 

The  accompanying  illustration,  Fig.  5,  gives  a  good  view  of  a  Babcock  &  Wilcox 
boiler  before  it  is  set.  It  will  be  noticed  that  these  boilers  are  equipped  both  with 
superheater  and  chain-grate  stokers.  This  particular  boiler  has  a  heating  surface  of 
2,933  square  feet,  which  is  made  up  of  two  drums  36  inches  in  diameter  and  fourteen 
rows  of  ten  tubes,  each  18  feet  long.  There  is  a  special  header  between  the  grates  and 
the  fire  wall,  in  which  a  rapid  circulation  of  water  will  be  created;  this  will  protect 
the  fire  wall  from  heat. 

The  superheater  has  a  heating  surface  of  410  square  feet,  while  the  grate  has  60 
square  feet;  as  this  is  9  feet  3  inches  long,  it  has  necessarily  to  extend  in  front  of  the 
boiler,  forming  an  extended  furnace. 

Size.  —  The  type  and  various  other  features  of  boilers  having  been  determined, 
the  next  point  for  consideration  is  the  number  of  units  and  the  size  of  each.  Careful 
consideration  must  be  given  to  the  quantity  of  steam  required  at  various  periods  in  the 
operation  of  the  plant.  The  supply  required  being  comparatively  constant,  the  numter 
of  units  may  be  fewer  than  when  the  required  supply  varies  considerably  at  different 
times.  The  units  should  be  of  such  a  number  and  so  proportioned  that  the  smallest 
amount  of  coal  is  consumed  in  the  development  of  the  power  required  for  any  par: 
ticular  period  of  operation,  and  provision  should  be  made  for  any  particular  tnit  or 
units  to  be  put  out  of  service  without  unnecessary  forcing  of  the  ether  units,  which 
condition  may  be  imposed  in  the  operation  of  the  plant  when  various  amounts  of  power 
are  required  to  be  developed  and  delivered,  or  when  a  particular  unit  is  in  need  of 
repairs.  For  instance,  in  a  case  where  five  units  might  be  determined  upon  as  the  nec- 
essary numter  to  supply  the  required  power,  the  modern  practice  is  to  install  six,  the 
additional  unit  being  used  in  the  interval  required  to  make  repairs  on  another  unit,  or 
it  may  also  be  brought  into  service  to  develop  an  output  above  the  normal  rating.  Until 
recently  the  practice  has  been  to  limit  the  size  of  the  individual  unit  to  5,000  or  6,000 


BOILERS.  93 

square  feet  of  heating  surface,  but  some  plants  have  been  constructed  or  are  in 
process  of  construction,  both  in  Great  Britain  and  America,  in  which  the  size  of  each 
unit  has  been  increased  to  11,000  square  feet  (see  Figs.  3  and  4).  In  view  of  these 
facts  we  might  say  that  in  general  the  size  of  each  unit  will  be  as  large  as  economically 
possible,  considering  the  number  of  units  required  to  make  provision,  as  above  stated, 
for  repairs,  for  forcing  the  boilers  and  for  varying  demands  upon  the  plant. 

In  regard  to  the  size  of  the  boiler,  this  is  usually  measured  by  the  heating  surface. 
American  practice  is  to  rate  boilers  not  only  by  the  heating  surface,  but  as  so  many 
"boiler  horse-power."  One  boiler  horse-power  being  defined  as  equivalent  to  an 
evaporation  per  hour  of  30  pounds  of  water  from  and  at  100°  Fahr.  to  steam  at  70  pounds 
pressure,  or  equal  to  an  evaporation  of  34^  pounds  of  water  per  hour  at  and  from 
212°  Fahr.  This  value  of  a  boiler  horse-power  was  made  standard  by  the  committee 
of  the  Centennial  Exposition  held  in  1876,  and  has  since  been  incorporated  in  the 
code  of  standards  adopted  by  the  American  Society  of  Mechanical  Engineers.  The 
immediate  reason  for  adopting  a  value  of  30  pounds  instead  of  some  other  quantity 
was  owing  to  the  fact  that  the  prevailing  types  of  good  engines  at  the  time  of  the 
Centennial  Exposition  required  about  30  pounds  of  steam  per  horse-power  hour.  Since 
the  adoption  of  these  standards  the  development  of  boiler  design  has  been  such  that  the 
conditions  governing  the  adoption  of  these  standards  no  longer  prevail,  owing  to  the 
fact  that  instead  of  a  pressure  of  70  pounds  we  may  frequently  use  a  pressure  from 
170  to  250  pounds,  and  even  higher.  Furthermore,  owing*  to  the  more  refined 
boiler-house  equipment  of  modern  times,  the  temperature  of  the  feed  water  is  con- 
siderably higher  than  at  the  time  of  the  adoption  of  these  standards;  modern 
practice  using  water  heated  even  higher  than  212°. 

Of  still  greater  moment  is  the  employment  of  superheated  steam,  to  which  condi- 
tion is  due  the  fact  that  steam  consumption  per  horse-power  is  considerably  reduced, 
not  taking  into  consideration  the  improvements  of  the  engines  to  be  served.  In  well- 
designed  American  power  plants  of  today  one  boiler  horse-power  actually  serves  from 
two  to  three  engine  horse-power,  as  shown  by  the  accompanying  table,  in  which  the 
ratio  between  a  kilowatt  and  the  rated  horse-power  for  various  power  plants  is  given  : 

BOILER   HORSE-POWER   PER   KILOWATT 

Metropolitan,  New  York 66 

Manhattan,  New  York 83 

Interborough,  New  York .75 

Kingsbridge,  New  York .55 

Waterside,  No.  r,  New  York 65 

Waterside,  No.  2,  New  York 80 

Port  Morris,  New  York 50 

Brooklyn  R.  T.  Co.,  New  York 71 

Boston  Edison  Co.,  Boston 82 

Delaware  Avenue,  Philadelphia 92 

Babcock  &  Wilcox  Boiler.  —  There  are  a  number  of  boilers  of  the  water-tube 
type  on  the  market,  all  of  which  more  or  less  fulfill  the  above-mentioned  requirements. 
Among  these,  and  perhaps  about  as  common  a  type,  both  in  America  and  Great 


94 


STEAM-ELECTRIC    POWER    PLANTS. 


Britain,  as  any  other,  is  the  Babcock  &  Wilcox  boiler.  Primarily  this  boiler  is  com- 
posed of  wrought-steel  tubes,  placed  in  an  inclined  position  and  connected  with  each 
other  and  with  a  horizontal  steam  and  water  drum.  The  inclined  position  of  the 
tubes  is  used  for  the  purpose  of  securing  a  rapid  circulation  of  the  water  and  conse- 
quent rapid  evaporation.  Vertical  passages  are  provided  at  each  end,  between  headers 
and  drum,  and  usually  a  mud  drum  is  connected  at  the  end  and  lowest  point  of  the 
boiler.  The  headers,  which  are  made  of  wrought  iron,  are  in  one  piece,  and  of  such 
a  form  that  the  tubes  when  in  position  are  staggered.  This  arrangement  places  each 
row  of  tubes  directly  over  the  spaces  in  the  previous  row,  thus  forcing  the  hot  gases 
to  impinge  upon  the  surfaces  of  the  various  tubes.  The  tubes,  which  are  made  of 
wrought  mild  steel,  are  expanded  into  the  headers  at  both  ends;  the  number  of  tubes 
required  depending,  of  course,  upon  the  size  of  the  boiler.  For  instance,  a  boiler  of 


FIG  6.     Stirling  Boiler  and  Superheater. 


6,000  square  feet  of  heating  surface,  or  commonly  called  600  horse-power,  employs  a 
maximum  of  about  14  tubes  per  vertical  header,  and  requires  21  such  headers;  3  drums 
of  42  inches  in  diameter  and  23  feet  long  would  be  used.  The  water  tubes  in  this  type 
of  boiler  are  usually  18  feet  long  and  4  inches  in  diameter.  At  the  rear  of  the  boiler 
and  connected  with  the  lowest  point  of  the  rear  headers  is  a  cylindrical  mud  drum, 
provided  with  two  2^-inch  blow-off  pipes.  In  many  instances  where  pure  feed 


BOILERS. 


95 


water  is  to  be  had  this  mud  drum  is  entirely  omitted,  and  a  small  horizontal  header  is 
used  in  its  place.  The  vertical  sections  are  connected  with  the  drums  by  means  of 
short  lengths  of  tubing  expanded  into  the  headers  and  drums. 

Stirling  Boiler.  — The  Stirling  boiler,  one  of  the  most  efficient  boilers,  consists  of 
three  upper  or  steam  drums  and  a  lower  or  mud  drum,  made  of  flange  steel,  and  con- 
nected by  charcoal  iron  or  soft  steel  tubes.  The  upper  drums  rest  in  saddles  and  are 


FIG.  7.     Eight  250  H.  P.  Wickes  Vertical  Water  Tube  Boilers  at  the  Plant  of  Philadelphia 

and  Reading  R  R. 

supported  by  a  framework  of  "I"  beams,  while  the  mud  drum  is  sustained  entirely 
by  the  tubes  connecting  it  with  the  drums  above.  The  connecting  tubes  arc  bent 
slightly  so  as  to  admit  of  their  radial  entrance  into  the  drums,  which  feature, 
together  with  the  manner  of  supporting  the  mud  drum,  gives  the  boiler  perfect  freedom 
for  expansion  and  contraction. 

By  means  of  baffles  the  furnace  gases  are  directed  along  the  entire  length  of  the 
banks  of  tubes  to  the  smoke  exit  in  the  rear.  The  feed  water  is  admitted  to  the  rear 
drum  and  follows  a  course  of  circulation  opposite  in  direction  from  that  of  the  furnace 
gases.  In  the  flow  downward  through  the  rear  bank  of  tubes  a  large  proportion  of 
the  contained  impurities  precipitate  and  descend  to  the  lower  drum,  whence  they  are 
blown  out. 


96 


STEAM-ELECTRIC    POWER    PLANTS. 


The  boiler  is  surrounded  on  the  rear  and  two  sides  by  a  brick  setting,  and  the  front 
is  made  either  entirely  of  cast  iron,  or  cast  iron  and  pressed  steel. 

For  cleaning  and  inspection  purposes  the  setting  is  provided  with  doors  located  at 
convenient  points;  and  access  to  the  interior  of  the  boiler  proper  is  gained  through  a 


FIG.  8.    Combined  Lancashire  and  Return  Tubular  Boiler  with  Superheater  attached. 

manhole  in  one  end  of  each  drum.  Ordinarily  it  is  sufficient  to  flush  out  the  interior 
of  the  tubes  by  means  of  a  hose,  but  if  the  feed  water  is  impure  a  turbine  cleaner  is 
used. 


BOILERS. 


97 


The  furnace  of  the  boiler  is  lined  with  fire  brick  on  all  sides,  and  an  arched  roof  of 
fire  brick  is  also  provided,  the  effect  of  which  is  materially  to  aid  in  burning  the  fuel 
by  radiating  heat  upon  it  and  preventing  the  chilling  effect  which  usually  follows  when 
fresh  fuel  is  charged. 

Wickes  Boiler.  — Another  type  of  vertical  boiler  which  is  used  considerably  in 
the  West,  where  the  vertical  type  has  been  more  generally  adopted  than  in  the  East, 
is  the  Wickes,  shown  in  Fig.  7.  This  boiler  consists  primarily  of  two  cylinders,  joined 


FIG.  9.     Lindhaus  Water  Tube  Boiler  with  Hering  Superheater  and  Dubiau  artificial  water 
circulating  apparatus.     Heating  Surface  of  Superheater  \  of  that  of  Boiler. 


together  by  straight  tubes,  and  divided  by  a  fire-brick  tile  passing  through  their  center 
and  dividing  the  boiler  into  two  compartments.  The  whole  is  then  erected  in  a  verti- 
cal position  and  surrounded  by  brickwork.  The  two  cylinders  are  duplicates  in  their 
diameter  and  general  construction,  but  differ  in  height  and  arrangement  of  convex 
heads. 

The  fire-brick  dividing  wall  or  baffle  plate  gives  the  gases  of  combustion  two  com- 
plete sweeps  through  the  entire  length  of  the  boiler,  and  the  second  sweep  from  above 
downward.  The  heat  in  its  double  passage  surrounds  completely  and  closely  the 
tubes  in  both  compartments.  The  water  line  in  the  boiler  is  maintained,  in  the  steam 
drum,  at  a  sufficient  height  to  insure  the  complete  submersion  of  the  tubes. 


98 


STEAM-ELECTRIC    POWER    PLANTS. 


On  a  level  with  the  water  line,  and  extending  over  the  tubes  in  the  front  compart- 
ment, is  the  baffle  plate,  which  deflects  the  rising  water,  commingled  with  its  steam, 
directly  to  the  "downcomers." 


FIG.  10.    Boiler  Unit  of  the  59th  Street  Plant,  New  York.     B.  &  W.  Boiler,  Forster  Super- 
heater and  Roney  Stoker. 

The  setting  of  the  boiler  is  of  brickwork,  arranged  so  that  it  is  entirely  independent 
of  the  boiler  and  free  to  expand  and  contract,  and  to  allow  the  boiler  to  do  the  same. 


MECHANICAL  STOKERS  AND  GRATES.  99 

The  foundations  are  so  designed  that,  by  means  of  a  door  through  the  circular  brick- 
work, a  man  can  enter  underneath  the  boilers,  examine  or  adjust  the  blow-off  pipes  and 
rivets,  and  see  that  the  bottom  of  the  mud  drum  is  kept  painted. 

Foreign  Types  of  Boilers.  —  The  foregoing  represent  but  three  types  of  boilers. 
There  are,  however,  both  in  America  and  Europe,  a  variety  of  types  and  designs  suc- 
cessfully employed  in  central  stations.  For  example,  a  boiler  very  popular  on  the 
Continent  of  Europe  is  shown  in  Fig.  8.  This  boiler  is  a  combined  Lancashire  and 
return  tubular,  with  a  superheater  attached.  An  illustration,  showing  the  boiler  room 
of  the  light  and  power  plant  "Bille"  in  Hamburg,  in  which  these  boilers  are  used,  is 
given  in  Fig.  i. 

An  interesting  type  of  German  water-tube  boiler  is  seen  in  Fig.  9.  This  boiler  is 
equipped  with  Hering  superheater,  having  a  heating  surface  one-third  that  of  the 
boiler.  It  will  be  noticed  that  an  arrangement  is  provided  for  by-passing  the  super- 
heater. At  the  front,  in  the  steam  drum,  there  is  installed  a  Dubiau  artificial  water 
circulating  apparatus.  It  consists  of  a  number  of  tubes  extending  above  the  water 
line,  the  rising  water  from  the  front  header  spills  over  the  tops  of  these  tubes,  thereby 
creating  a  more  rapid  evaporation. 

Conclusion.  — Whatever  type  of  boiler  be  adopted,  either  tubular  or  water-tube, 
vertical  or  horizontal,  the  unit  should  be  compact,  in  order  to  prevent  unnecessary  loss 
of  heat  from  leakage  and  radiation  and  also  for  economy  of  floor  space.  The  super- 
heater, when  installed,  should  occupy  suitable  space  in  the  hot  gases.  This  may  be 
done  without  increasing  the  height  or  width  of  certain  boilers,  still  having  the  required 
amount  of  surface  to  produce  the  proper  temperature.  This  can  easily  be  accom- 
plished, as  may  be  seen  in  Fig.  9,  where  the  small  tubes  of  which  the  superheater  gen- 
erally consists  are  bent  to  suit  the  condition.  The  heating  surface  of  the  superheater 
amounts  to  one-third  that  of  the  boiler. 

Where  economizers  are  installed  they  should  be  arranged  as  close  as  is  possible, 
in  order  to  have  the  benefit  of  the  hottest  gases.  Accessibility,  however,  is  a  feature 
which  should  not  be  overlooked. 

MECHANICAL    STOKERS    AND    GRATES. 

Advantages  and  Disadvantages.  —  Mechanical  stokers  are  employed,  first,  to  dis- 
pense with  the  services  of  expert  firemen;  secondly,  to  give  more  uniform  temperature 
throughout  the  furnace;  thirdly,  to  reduce  the  coal  consumption. 

The  first  item  is  of  great  importance,  where  skilled  labor  is  scarce;  while  where 
skilled  labor  is  easily  obtainable  and  coal  is  expensive,  it  is,  in  the  opinion  of  the  writer, 
preferable  not  to  use  mechanical  stokers.  The  second  item  is  undoubtedly  in 
favor  of  the  mechanical  stoker,  for  with  hand  firing  it  is  impossible  to  prevent  chilling 
of  the  boiler  when  the  fire  doors  are  open.  The  reduction  in  coal  consumption  may 
only  be  secured  where  unskilled  labor  is  employed  as  above  mentioned.  A  boiler 
may  be  much  more  economically  forced  by  hand  than  with  a  mechanical  stoker.  It 
is  frequently  claimed  that  mechanical  stokers  may  be  forced  for  a  70  to  100  per  cent 


THE 

UNIVERSITY 


IOO 


STEAM-ELECTRIC    POWER    PLANTS. 


overload;  in  a  case  like  this,  the  stokers  have  evidently  been  designed  too  small  for 
their  work,  for  no  boiler  should  be  forced  to  this  extent. 

Another  important  claim  is  that  the  combustion  is  more  complete  than  with  hand 
firing;  this  is  due  to  the  fact  that  the  fire  is  continually  stirred  by  the  movement  of 
the  bars,  and  ashes  are  removed  as  fast  as  formed,  giving  a  free  supply  of  air.  A 
good  assistance  in  preventing  smoke  is  the  coking  arch,  with  which  practically  all 
mechanical  stokers  are  equipped.  These  arches  may  also  be  employed  with  a  hand- 
fired  furnace  with  practically  the  same  result.  Where  it  is  the  intention  to  prevent 
smoke,  heated  air  may  be  supplied  to  the  furnace,  over  the  fire,  at  a  point  where  the 


FIG.  i.     Interior  of  Boiler  Room,  Stuart  Street  Plant,  Manchester. 

smoke  passes  between  the  coking  arch  and  the  fire  bridge.  In  some  instances  steam 
is  admitted  over  the  fire  to  induce  air  to  flow  in;  this  may  result  in  preventing  smoke 
with  suitable  conditions.  Steam  is  in  some  cases  discharged  under  the  grate  to  prevent 
the  formation  of  clinkers  and,  of  course,  will  add  to  the  operating  cost.  In  place  of 
a  device  of  this  kind,  an  efficient  steam  blower  would  produce  better  results  with  but 
slight  additional  cost  of  operation. 


MECHANICAL    STOKERS    AND    GRATES. 


101 


Systems  of  Stokers.  —  Mechanical  stokers  may  be  classified  as 

CHAIN  GRATES.         INCLINED  GRATES.       UNDERFEED. 


FIG.  2.     Green  Travelling  Link  Grate. 


HOPPER  END 
THROAf-PLATE^X 


FEED-WHEEL 
AGITATOR-SECTOR 
SHEATH-NUT. 
AGITATOR 
LOCK-NUTS 
CONNECTING-ROD 
STOKER-SMAFT. 
•DUMPING-GRATE  HANDLE 
GUARD-ROD 


BRIOGEWALL  ANGLE 
DUMPING-GRATE  BEARER 


FIG.  3.     Roney  Mechanical  Stoker. 


IO2 


STEAM-ELECTRIC    POWER    PLANTS. 


Chain  grates  receive  the  coal  at  the  front  of  the  furnace,  and  travel  slowly  towards 
the  fire  bridge,  where  the  ashes  are  dumped.  The  chain  is  endless  and  cleans  itself. 
In  the  accompanying  illustration,  Fig.  2,  which  represents  the  Green  traveling  link 
chain,  it  will  be  seen  that  only  one-third  of  the  chain,  nearest  the  fire  bridge,  extends 
over  the  ash  pit,  while  the  remainder  is  suspended  over  the  low  pit,  which  collects 
whatever  coal  may  fall  through  the  grate.  This  coal  has  to  be  removed  as  in  all  other 
overfeed  mechanical  stokers  and  shoveled  by  hand  into  the  receiving  hopper,  which 
is  seen  at  the  left  of  the  illustration.  The  rod  "A"  is  operated  by  an  eccentric  on  the 
shaft  above  the  boiler,  and  transmits  motion  to  the  mechanism  of  the  grate.  A  number 
of  boilers  may  be  operated  by  one  engine.  The  grate  is  readily  removable ;  it  is  sup- 


Stoker-firing 


FIG.  4.     Steam  Pressure  Diagram,  Boiler  fired  by  Hand  and  Mechanical  Stoker. 

ported  on  a  wheeled  frame  and  may  be  entirely  pulled  out  for  inspection  and  repairs, 
which  is  unquestionably  a  great  advantage. 

A  type  of  mechanical  stoker  also  frequently  used  is  the  Roney,  of  the  inclined  type. 
This  grate  is  also  operated  from  a  shaft  connected  to  several  grates.  The  illustration, 
Fig.  3,  shows  that  the  grates  have  an  oscillating  motion.  The  ashes  are  dumped  at 
the  lowest  point  or  dumping  grate.  Fig.  4  shows  two  recording  gauge  charts,  that 
on  the  left  recording  the  steam  pressure  while  the  boiler  was  hand-fired,  and  that  on 
the  right  from  the  same  boiler,  after  being  equipped  with  a  Roney  stoker. 

When  employing  overfeed  mechanical  stokers  it  is  necessary  to  provide  a  receiving 
device  for  the  fine  coal  falling  through  the  grate,  so  that  this  may  be  saved.  It  is 
claimed  that  this  coal  may  amount  to  5  per  cent  of  the  entire  amount  consumed,  the 
percentage  varying  with  the  size  of  coal  burned  and  type  of  grate.  Where  boilers  of 
from  500  to  600  horse-power  have  been  installed,  it  takes  one  man  to  clean  up  the 
coal  falling  through  the  grates  of  six  boilers. 

The  underfeed  stokers,  of  which  the  "American"  and  "  Jones"  are  the  more  prom- 


MECHANICAL    STOKERS    AND    GRATES. 


103 


inent,  operate  by  forcing  the  coal  on  the  grates.  The  "American"  uses  a  gimlet- 
pointed  large  screw,  thus  forcing  the  coal  gradually  upwards,  distributing  on  both 
sides  of  sloping  grates.  , 

The  "Jones"  stoker  is  operated  by  a  steam-actuated  piston,  which  forces  the  coal 


FIG.  5.     Jones  Underfeed  Stoker  at  the  Commerce  Street  Plant  Milwaukee. 

directly  on  the  grates  under  the  fire.     This  plunger  may  be  operated  automatically 
or  by  hand.     Fig.  5  represents  the  application  of  the  above-mentioned  stoker  to  water- 


FIG.  6.     McClave  Grate. 

tube  boilers  in  the  Commerce  Street  plant  of  the  Milwaukee  Electric  Railway  and 
Light  Company.  The  coal  may  be  fed  to  mechanical  stokers,  either  from  overhead 
bunkers  through  chutes,  as  seen  in  Fig.  5,  or  shoveled  into  hoppers  by  hand. 


104 


STEAM-ELECTRIC    POWER    PLANTS. 


The  motive  power  supplied  to  a  mechanical  stoker  is  usually  steam;  one  shaft  may 
operate  several  boilers;  if  a  single  stoker  has  to  be  cut  out  the  mechanism  is  unlinked. 
In  selecting  a  stoker  the  kind  and  size  of  coal  to  be  used  should  first  be  determined, 
so  that  the  amount  of  coal  falling  through  the  grate  will  be  minimized. 

Grates.  — For  hand  firing  there  are  two  styles  of  grate  commonly  used;  viz.,  station- 
ary and  shaking  grates.  The  latter  is  shown  in  Fig.  6,  which  represents  a  McClave 


FIG.  7.     Furnace  Setting  with  Roney  Stoker,  note  receptacle  for  collecting  fine  coal  and 
soot  chute.     Port  Morris  Plant,  New  York. 

grate.     The  grate  bars  are  connected  in  groups,  which  may  be  separately  shaken  or 
dumped.     The  operation  of  cleaning  fires  is  as  follows: 

The  hot  coal  is  first  pushed  to  the  rear  of  grate,  leaving  the  front  covered  with  ashes ; 
the  front  section  is  then  dumped,  depositing  ashes  into  ash  pit.  The  fire  is  then 
pulled  upon  the  front  section  and  the  same  operation  is  performed  with  the  rear 
section,  the  fire  is  then  redistributed.  Stationary  grates  are  too  well  known  to  require 
description. 

COAL. 

Introductory.  —  Coal  should  be  intelligently  selected  on  the  basis  of  its  cost  per  heat 
unit  contained,  instead  of  on  its  cost  per  ton.  Coal  is  the  fuel  most  extensively  used, 
it  being  the  most  widely  distributed  fuel,  and  the  most  convenient  for  the  purpose. 
It  is  a  fossil  of  vegetable  origin,  and  the  variations  in  its  nature  are  attributable  to  the 
variations  in  its  origin.  Coal  from  the  same  seam  does  not  vary  very  greatly  in 
its  nature  or  characteristics,  and  generally  these  characteristics  are  the  same  for  all 
coal  mined  in  a  certain  district,  but  at  the  same  time  the  thermal  value  of  the  coal 


COAL.  105 

from  the  same  mine  may  vary  greatly.  For  this  reason  it  is  important  that  the  heat 
value  of  each  shipment  of  coal  should  be  determined,  whether  from  the  same  mine  or 
from  the  same  district.  As  a  general  rule  the  commercial  designation  of  the  coal  is 
based  on  the  district  in  which  it  is  mined. 

From  a  chemical  point  of  view  coal  is  divided  into  two  main  classes,  anthracite  and 
bituminous.  Anthracite  is  a  word  of  Greek  origin,  meaning  carbon  or  coke;  the  fuel 
being  so  called  probably  because  it  is  that  which  contains  the  largest  percentage  of 
fixed  carbon.  Bituminous  is  of  Latin  origin,  meaning  containing  or  resembling  pitch 
or  bitumen.  There  are  a  number  of  degrees  in  the  nature  of  these  two  qualities  of 
coal,  which  are  graded  commercially  as  semi-bituminous,  gas  or  cannel  coals  and  lig- 
nites. A  designation  is  also  made  of  semi-anthracite.  Some  of  the  coals  are  very 
soft,  while  others  are  of  a  hard  nature ;  the  most  recent  formations  or  lignites  being  the 
softest,  and  very  often  the  classification  is  made  of  "hard"  and  "soft"  coal  in  place 
of  anthracite  and  bituminous.  Anthracite  coal  is  supposed  to  be  the  oldest  and  deep- 
est coal  formation  in  existence.  The  veins  exist  principally  in  the  United  States  of 
America,  and  also  to  some  extent  in  South  Wales  in  the  neighborhood  of  Swansea;  in 
some  parts  of  Scotland  and  in  some  parts  of  France,  in  the  neighborhood  of  Grenoble; 
in  the  south  of  Russia  and  in  the  Osnabruck  district  of  Westphalia,  Germany.  The 
semi-anthracite  or  semi-bituminous  coal  is  largely  found  in  the  central  portions  of 
Pennsylvania  and  some  of  the  Western  States  of  America;  enormous  fields  of  it  exist 
in  Wales,  it  being  often  called  "Cardiff"  or  "Welsh"  coal.  It  is  also  found  in  Bel- 
gium. Hard  bituminous  or  cannel  coal  is  principally  used  for  the  making  of  gas, 
rarely  for  generating  steam.  It  is  mined  in  the  Midlands  and  in  Lancashire  in  Eng- 
land; in  West  Virginia,  America;  to  some  extent  in  Australia,  and  in  a  few  localities 
on  the  Continent  of  Europe.  Soft  or  bituminous  coal  is  the  most  widely  distributed, 
with  the  possible  exception  of  lignite.  Extremely  large  fields  of  coal  exist  in  Scotland; 
in  various  portions  of  England;  in  the  Ruhr  coal  district,  Germany;  in  the  north  of 
France;  in  Australia,  Russia,  the  United  States,  New  Zealand  and  a  number  of  the 
Asiatic  countries.  Lignite  is  distributed  very  widely,  but  is  not  used  largely  for  fuel, 
except  in  the  immediate  vicinity  of  the  places  where  it  is  produced,  being  usually  a  poor 
quality  and  filled  with  refuse,  and  it  is  hardly  considered  as  fuel  for  a  modern  power 
station.  Bituminous  coal  can  be  separated  into  two  classes,  the  coking  and  the  non- 
coking  coals;  the  distinction  being  that  the  coking  coals  when  heated  conglomerate 
into  a  pitchy  mass,  from  which  the  volatile  products  are  gradually  distilled,  previous 
to  the  combustion  of  the  fixed  carbon;  while  the  non-coking  coals  disintegrate  and 
break  up  in  burning. 

Heat  Value.  —  The  accompanying  table,  as  given  in  "Steam"  of  Babcock  &  Wil- 
cox,  Ltd.,  London,  indicates  the  principal  components,  and  the  heating  value  of  the 
various  commercial  coals  produced,  which  are  burnt  under  boilers.  It  is  obvious  that 
sharp  lines  of  demarcation  cannot  be  drawn  between  the  various  kinds  of  coal;  that 
is,  each  classification  is  only  approximate,  and  one  form  gradually  merges  into  the 
other. 


io6 


STEAM-ELECTRIC    POWER    PLANTS. 


TABLE  I.  —  HEATING   POWER  OF    COALS    OF   ENGLAND,  UNITED    STATES,  GERMANY, 
FRANCE,  BELGIUM,  AUSTRIA-HUNGARY,  AUSTRALIA,    JAPAN   AND   TRANSVAAL. 


Co.u.s,  LOCALITY  or  BEDS. 

B.T.U. 

CALORIES. 

NATU  RE  . 

GREAT  BRITAIN. 
Ebb\v  Yale,  1848  f    «j 

16,214 

8,008 

l  Almost  pure  Anthracites    having  84  to  89 

Powell  Duffryn,  1848   .... 
Graigola,  1848       J 

15.715 
14,689 

8,710 
8,i=;2 

)                        per  cent  of  carbon. 

Llangennech,  1848    1    — 

14,008 

8,318 

Smokeless  steam  coal. 

Llangennech,  1871    1    ^ 

14,964 

8,305 

Nixon's  Navigation  

15,000 

8,32s 

Called  smokeless 

Gwaun  Cae  Gurwen    

I  s,I23 

8,402 

Pure  hard  Anthracite. 

Newcastle  

I4,82O 

8,225 

!  Bituminous  coal,  having  77  to  8?  per  cent 

Derbyshire  and  Yorkshire    ... 

13,860 

7,602 

of  carbon 

Lancashire      

1  3,018 

7,724. 

Scotch     .    .                .        

12,870 

7,1  CQ 

Bituminous  coal,  having  78  per  cent  of  carbon 

UNITED  STATES. 
Pennsylvania                  .... 

14,221 

7,802 

Anthracite    having  88  per  cent  of  carbon 

Pennsylvania                  

I1.IA.1, 

7.2Q3 

Cannel  coai. 

Pennsylvania     
Kentucky 

I3.ISS 

U.3QI 

7.301 

7,087 

Bituminous  coking. 
Bituminous  coking. 

Kentucky                     

i  ^,108 

8,434 

Cannel  coal. 

Kentucky    

0,326 

c,i7; 

Lignite  (good). 

Illinois     

I  3,123 

7,283 

Bituminous  coking. 

Indiana       

14,146 

7.8<u 

Bituminous  coking. 

Indiana   

I  3,007 

7,268 

Cannel  coal. 

Yirginia  

13,100 

7,270 

Bituminous  coking. 

Arkansas                         .    .  '  

0,21  <: 

^,114 

Lignite  (good). 

GERMANY. 

RHENISH  PRUSSIA. 
Dortmund                           .    .         f 

14,518 

8,066 

Cannel  coal. 

Witten     \ 

1C   I2s 

8,403 

Bochum  J 

17,514 

7,508 

«           « 

Bommern                                              -5 

13,212 

7,  -2  40 

Short  flame  coal,  Semi-anthracite. 

Essen  [    ^ 

I4,o8s 

8,325 

Cannel  coal. 

Saar-Coal    

11,511 

6.^0=; 

SAXONY. 
Zwickau      

11,964 

6,647 

Cannel  coal. 

Hohndorf                     .                          .    . 

1  1,343 

6,302 

Oelsnitz  .    .        

10,674 

5,970 

«           « 

LOWER  SAXONY,  ANHALT  &  BRUNSWIG 
Unseburg    

=5,760 

3,205 

Brown  coal  or  lignite,  low  grade. 

Atzendorf    

6,444 

3,580 

Neudorf                           

6,00  3 

3,385 

t<             «            «               ti 

Gorzig     

7,852 

2,140 

n             «            (i               «< 

Halle  a    S                       

4,i6c 

2,  314 

!<                                «                             «                                     <« 

Bitterfeld    

3,870 

2,128 

«                                «                             <l                                     (1 

Naumburg 

4,=;  6? 

2,5.35 

„ 

COAL. 

TABLE   I.  —  Continued. 


lO/ 


COALS,  LOCALITY  OF  BEDS. 

B.T.U. 

CALORIES. 

NATURE. 

HANOVER. 
Osnabriick      

10,780 

c,oo4 

Semi-anthracite,  low  grade. 

Obernkirchen     

12,718 

7,066 

Bituminous. 

SILESIA  (PRUSSIA). 
Carlssegen       

10,422 

;,7oo 

Long  flaming,  Semi-bituminous. 

Myslowitz  

10,7^8 

5,977 

\Vaterloa         .        .                

1  1,412 

6,740 

« 

Kdnigshiitte    

12,247 

6,804 

« 

Paulusgrube  

12.421; 

6,OO  7 

«            a                      a 

Waldenburg    

12,67.7 

7,021 

« 

Brandenburg      

12,  IQ7 

6,774 

a            n                      <« 

Neurode      

12,707 

7,441 

«            «                      « 

Freienstein      

0,6^i 

C.-*62 

«            «                      « 

Maxgrube  

10,087 

5  ,604 

«            K                      «< 

BAVARIA. 
Hanshamer  coal    

0,821 

c,4c6 

Lignite  or  brown,  low  grade. 

Peipenberg     

8,186 

4,548 

Penzberg     

8,021 

4,056 

« 

FRANCE. 
Anthracite  de  la  Mayenne  

is.^66 

8,646 

Anthracite. 

Anthracite  de  Lamure  (Isere)     .    .    . 

BASSIN  DU  BAS-DE-CALAIS. 
Maries     

13,782 
14,17=; 

7,657 

7,875 

« 
Bituminous  hard  coal. 

Bully   

15,120 

8,400 

hard  coal. 

Hessin     

IC,7C2 

8,520 

coking. 

Lens    

1^,258 

8,477 

hard  coal. 

Naux  

15,21:6 

8,476 

"            coking. 

1'Escarpelle     

15,400 

8,556 

coking. 

les  Courrieres     

14,265 

7,02^ 

Semi-bituminous  coal. 

BASSIN  DE  LA  SAONE. 
Blanzy     

17,127 

7.20-? 

Semi-bituminous  coal,  long  flame. 

Epinac    

14,086 

7,826 

Bituminous  coal,  long  flame. 

BASSIN  DE  LA  LOIRE. 
Rive-de-Gier,  puits  Henry  

15,481 

8,601 

Bituminous  hard  coal. 

Rive-de-Gier,  No.  i      

ic,  472 

8,506 

«                    « 

Rive-de-Gier,  Cimetiere  i    

14,407 

8,0  q  2 

long  flame. 

Rive-de-Gier,  Cimetiere  2    

I  ?,7OQ 

8,505 

Rive-de-Gier,  Couson  

14,770 

8,206 

«                                    M                                  « 

BASSIN  DE  L'AVEYRON. 
Lavaysse     

14,630 

8,128 

Bituminous  hard  coal,  long  flame. 

Ceral   

17,20? 

7,771; 

Semi-bituminous  coal. 

Bassin  d'Alais  Rochbelle 

IS.647 

8.601 

Bituminous  cokins. 

io8 


STEAM-ELECTRIC    POWER    PLANTS. 


TABLE  I .  —  Continued. 


COALS,  LOCALITY  OF  BFDS. 

B.T.U. 

CALORIKS. 

NATURE. 

BASSIN  DE  VALENCIENNES. 
Denain  Fosse  Renard  

15,244 

8,460 

Bituminous  coal,  long  flame. 

Denain  Fosse  Lelvet  i         ... 

15,100 

8,280 

Denain  Fosse  Lelvet  2     

Is,  3l6 

8,  coo 

«                                 tt 

St.  Wast,  Fosse  de  la  Reussitc  .    .    . 
St.  Wast    Grande  Fosse 

i5>105 
15,188 

8,392 
8,438 

"     short  flame         . 
11               u              u 

St.  Wast,  Fosse  Tinchon     
Anzin  Fosse  Chauffour 

15,082 

14,71:  7 

8,379 

7,074 

tl              .               11                           U 

Bituminous  coking. 

Anzin  Fosse  la  Cave 

I4,s;4Q 

8,08? 

Anzin  Fosse  St.  Louis      

I5,7Q7 

8,554 

u 

Fresne    Fosse  Bonnepart 

15,228 

8,460 

Semi-bituminous  coal. 

Vieux-Conde  Fosse  Sarteau     .... 

15.409 

8,561 

BELGIUM. 

BASSIN  DE  MONS. 
Haut-flenu              

I4,C76 

8,008 

Semi-bituminous  hard  coal. 

Belle  et  Bonne,  Fosse  No.  21     ... 
Levant  du  flenu 

I4,326 
14,508 

7,959 
8,060 

Couchant  du  flenu        

14,446 

8,077 

« 

Midi  du  flenu    

I  4,?s  7 

8,085 

«                           «             u 

Grand-Hornu 

14,04.7 

8,7O2 

u                           it            « 

Nord  du  bois  de  Bossu    

14,407 

8,OO4 

It                         It           tt 

Grand-Buisson  

14,877 

8,26? 

tl                         It            It 

Escouffiaux 

1^,217 

8.4CJ. 

u                           tt             tt 

St.  Hortense,  bonne  veine   . 

1^,107 

8.303 

tl                         It            « 

BASSIN  DU  CENTRE. 
Haine  St.  Pierre    

14,702 

8,  1  68 

Semi-bituminous  coking  coal. 

Bois  du  Luc 

I4,7c:8 

7,077 

La  Louviere       .        

1^,127 

8,404 

-it                    it         it 

Bracquegnies      

15,363 

8,575 

tt                    n         tt 

Mariemont     

15,168 

8,427 

n                    it         « 

Bascoup      .    .        

14,911 

8,284 

Bituminous  hard  coal. 

Sars-Longchamps      

14,895 

8,275 

Houssu    

14,945 

8,303 

«                «        it 

BASSIN  DE  CHAELEROI. 
St.  Martin,  Fosse  No.  3       

14,954 

8,708 

Semi-bituminous  coking. 

Trieukaisin    

15,069 

8,772 

Poirier,  Fosse  St.  Louie           .... 

14,421 

8,012 

« 

Bayemont,  Fosse  St.  Charles      .    .    . 
Sacre-Madame  

13,806 

15,204 

7,670 
8,447 

hard  coal. 

Sars-les-Moulins,  Fosse  No.  7    ... 
Carabinier-francaise  No.  2      .... 
Roton,  veine  Greffier   

15,125 
14,911 
14,311 

8,403 
8,284 
7,951 

«                      <( 

«                      « 

Pont-du-Loup    

14,947 

8,304 

u                              « 

AUSTRIA-HUNGARY. 

LOWER  AUSTRIA. 
Griinbach       .    .        

11,458 

6,366 

Semi-bituminous  coal. 

Thallern                     

7,0^7 

7,921 

Lignite  or  brown  coal. 

UPPER  AUSTRIA. 
Wolfseee-Trannthal 

6,006 

3,337 

Lignite  or  brown  coal. 

COAL. 


109 


TABLE    I.  —  Continued. 


COALS,  LOCALITY  OF  BEDS. 

B.T.U. 

CALORIES. 

NATURE. 

STYRIA. 
Leoben    

0,666 

r,-?7O 

Lignite  or  brown  coal. 

Fohnsdorf  

o  187 

5IO4 

Goriach  

6,222 

•3,4C7 

«              «<          « 

Koflach  

6867 

*  8is 

<<                     u              « 

Wies    

7.OO7 

A..A.A.1 

«              <«          « 

Trifail     

7  ??6 

«              it          « 

BOHEMIA. 
Kladno    

10  67? 

C   Oil 

Semi-bituminous  coal. 

Buschtehrad  

8,865 

4.  02? 

Libuschin   

Q  OOO 

c  coo 

«                   « 

Schlan     .    . 

7  Q7O 

A.  A.11 

«                   « 

Rakonitz-Lubna    

7,2(7 

A.  O32 

«                   <« 

Pilsen  

Q,?l8 

e,I77 

«                   « 

Schatzlar     

O  ?<J2 

C   1O  7 

if                   « 

Aussie 

6,408 

7   ?6o 

Lignite  or  brown  coal. 

Dux     

7,8o8 

4  -??8 

«                              <£                   II 

Bilin    

8  182 

«               «          « 

Brux    

8,274 

A  CO7 

«               «          « 

MORAVIA. 
Rossitz    

12   C33 

M.  Ostram     

'  J  O\J 

12.623 

7  OI  7 

Gava  

4,8^8 

2.6OO 

Lignite  or  brown  coal. 

Goding   

5oc6 

2  800 

«              «<         « 

SILESIA. 
P.  Ostran  

I2.C6<1 

6  980 

Bituminous  coal. 

Orlan-Lazy    

I  2.T.  8O 

688? 

Poremba     

II.O57 

6.  1  A.  1 

«              n 

Karwin   

I3,O2I 

7,274. 

n              (t 

TT.O72 

6  672 

<i              it 

HUNGARY. 
Funfkirchen  

10,276 

"C.7OQ 

Cannel  coal. 

Anina  

ii  7t;6 

Cannel  coal 

Xeufeld  

5  .200 

2  889 

Lignite  or  brown  coal. 

Brennberg  . 

8,^2? 

A,  62? 

«               «          « 

Aika    

6  01  2 

7  841 

«               «          « 

Salgo-Tarjan      

7,o66 

A.  A.26 

«               <i          « 

Dorog-Annathal    

7  7OO 

A.  287 

«                     u              a 

Tokod     

8,069 

A.  A&1 

<«                              «                    K 

DALMATIA. 
Siveric     

8,087 

A.  A.m 

Lignite  or  brown  coal. 

ISTRIA. 
Arsa    

S6C7 

TRANSYLVANIA. 
Petrozseny      

II  286 

6  270 

8  692 

Lignite  or  brown  coal. 

BOSNIA. 
Zenica 

7.OII 

4.7SO 

Liernite  or  brown  coal. 

no 


STEAM-ELECTRIC    POWER    PLANTS. 


AUSTRALIA. 
COMPOSITION  OF  AUSTRALIAN  COALS. 

Specific  gravity 1-312 

Coke 68.0      per  cent 

Volatile  matter 31.7  " 

Sulphur 0.5  " 

Ash 8.3 

Australian  coal  is  jet-black  and  brilliant,  very  brittle,  and  breaks  with  a  cubical  fracture  like  New- 
castle coal.  It  is  bituminous  and  cokes  like  Newcastle  coal. 

JAPAN. 

Japanese  coal  is  slightly  more  bituminous  than  Welsh  coal. 

SOUTH   AFRICA. 

The  principal  coal  mining  areas  in  the  Transvaal  are  situated  at  Boksburg,  Brakpan  Springs,  Heidel- 
berg, Vereeniging,  and  Middleburg,  all  these  being  on  the  Stormberg  Bed  of  the  Karoo  Formation.  Of 
these  the  Middleburg  coal  is  generally  considered  the  best. 

In  Cape  Colony  the  Indwe,  Molteno,  Cyphergap  and  Sterkstroom  Collieries  are  the  best,  but  the  coal 
from  them  necessitates  the  use  of  extra  long  and  wide  grates,  and  the  frequent  cleaning  of  the  fires. 

The  coal  from  the  Cyphergap  Colliery  is  dirty  with  some  31  per  cent  of  refuse,  and  has  less  than  60  per 
cent  of  the  calorific  value  of  good  English  coal. 

The  coal  from  the  Indwe  Colliery  has  the  following  analysis: 


Specific  gravity 

Moisture 

Ash 

Coke 

Sulphur 

Non-combustible  constituents  . 
Combustible  constituents  .    .    . 

Fixed  carbon 

Volatile  combustible  constituent 
Heat  value  . 


1.51  per  cent 
1.44 

3-13 
79.42 
.69    « 


68.43 
49.28 
19.14 
9,200 


B.T.U. 


In  the  Orange  Colony  coal  is  found  at  Kronstad  and  Parys. 

In  Natal  the  coal  raised  at  Newcastle  and  Elandslaagte  is  of  good  quailty,  as  is  that  obtained  in  South 
Rhodesia,  at  Wankie. 

Character  of  Coal.  — The   following  table   gives   the   approximate   percentage   of 
fixed  carbon  and  volatile  matter  in  the  different  kinds  of  coal: 


TABLE  II.  — CHARACTER   OF  COAL. 


COAL. 

FIXED  CARBON 
PER  CENT  OF 
COMBUSTIBLE. 

VOLATILE 
MATTER 
PER  CENT  OF 
COMBUSTIBLE. 

100  to  92 

o  to    8 

Semi-anthracite      

02  to  8? 

8  to  13 

87  to  7? 

I?   to  2? 

Bituminous         

7?  to  SO 

2<:  to  so 

Lignite    

Below  50 

Over  50 

i 

COAL.  1  1  1 

The  theoretical  heat  value  which  a  fuel  develops  when  consumed  under  perfect 
conditions  can  only  be  attained  in  the  laboratory,  and  in  practice  this  result  is  only 
approximately  reached.  The  unit  in  which  this  heat  value  is  expressed  is  the  British 
Heat  Unit  or  thermal  unit,  which  is  used  in  Great  Britain  and  the  United  States,  and 
the  Calorie,  which  is  employed  in  the  countries  using  the  metric  system.  The  British 
Thermal  Unit  is  the  amount  of  heat  required  to  raise  the  temperature  of  a  pound  of 
water,  at  39°  Fahr.,  i°  Fahr.  The  abbreviation  is  B.T.U.  The  Calorie  is  the  amount 
of  heat  required  to  raise  the  temperature  of  i  kilogram  of  water  i°  at  4°  Centigrade,  the 
abbreviation  of  which  is  C.  To  convert  B.T.U.  per  pound  to  C.  per  kilogram  divide 
by  3.968  and  vice  versa. 

Analysis.  —  The  elements  in  the  coal  which  have  a  heat  value  are  the  carbon,  both 
fixed  and  volatile,  hydrogen  and  sulphur.  Coal  also  contains  some  water,  which, 
requiring  heat  for  its  evaporation,  detracts  proportionately  from  the  thermal  value  of 
the  fuel.  For  practical  purposes  the  carbon  and  hydrogen  alone  should  be  taken  into 
consideration  in  determining  the  heating  value  of  the  coal  from  its  analysis;  either  the 
approximate  or  the  ultimate  analysis  may  be  used,  as  may  be  available.  In  most  cases, 
however,  the  approximate  analysis  alone  can  be  obtained,  as  the  ultimate  analysis  of 
coal  is  rather  difficult  and  not  often  given. 

For  computing  the  heating  value  of  coal  in  B.T.U.,  under  theoretically  perfect 
conditions,  all  pure  carbon  and  hydrogen,  with  only  the  proper  amount  of  oxygen  added 
to  make  combustion  complete,  is  usually  calculated  by  the  use  of  Dulong's  formula: 

B.T.U.  =  i4S(C-f-4.28rH~         +  0.28  S). 


In  this  formula  the  elements  are  designated  by  the  letters  : 

C  =  Carbon. 
H  =  Hydrogen. 
O  =  Oxygen. 
S  =  Sulphur. 

The  above-mentioned  method  of  determining  the  heat  value  of  the  coal  is  theoret- 
ical, the  actual  heat  value  as  determined  by  laboratory  experiment  may  vary  from  it 
5  per  cent  to  10  per  cent;  much  greater  variation  will  be  found  if  the  attempt  is  made 
to  determine  the  heating  value  by  the  amount  of  water  evaporated  under  practical 
service  conditions  in  the  boiler,  this  last  giving  the  lowest  value  of  all.  In  the  labora- 
tory the  heating  value  of  the  coal  is  determined  by  the  use  of  the  calorimeter,  a  number 
of  forms  of  which  have  been  devised.  The  simplest  and  most  convenient  is  that  of 
Mahler,  which  is  a  modification  of  the  Berthelot.  In  this  instrument  combustion  takes 
place  in  an  atmosphere  of  oxygen  gas  inside  of  a  metal  bomb.  This  bomb  is  submerged 
in  water  of  known  weight.  The  sample  of  coal  to  be  tested  is  finely  powdered,  weighed 
and  suspended  on  a  platinum  plate  in  the  center  of  the  bomb,  after  which  the  cover 
is  screwed  on  and  oxygen  pumped  in  through  a  valve  at  the  top;  a  pressure  of  20  to  25 
atmospheres  per  square  cm.  (300  to  370  pounds  to  the  square  inch)  being  used  to  insure 


112 


STEAM-ELECTRIC    POWER    PLANTS. 


a  large  excess  of  oxygen  when  combustion  takes  place.  The  bomb  is  then  placed 
in  water  which  is  constantly  stirred  until  the  whole  apparatus  comes  to  the  same 
temperature,  and  enough  readings  are  taken  from  a  thermometer  to  establish  the  rate 
of  radiation  under  the  conditions  existing  before  combustion.  It  is  well  to  have  the 
water  at  the  same  temperature  as  the  room,  or  slightly  above  it.  When  all  is  ready 
the  coal  sample  is  ignited  by  means  of  an  electric  current,  passed  through  a  fine 
iron  wire,  suspended  from  terminals  inside  the  bomb,  in  such  a  way  as  to  touch  the 
coal.  This  wire  fuses  upon  the  passage  of  the  current  and  ignites  the  coal,  which, 
owing  to  the  atmosphere  of  oxygen,  burns  rapidly  and  completely,  giving  up  its  heat  to 
the  walls  of  the  bomb,  from  which  it  passes  to  the  water.  The  rise  in  the  temperature 
of  the  water  is  carefully  noted,  the  observations  being  taken  until  the  whole  arrives  at 


FIG.  i.     Calorimeter  of  M.  Pierre  Mahler  for  Determining  the  Heating  Value  of  Fuels. 

EXPLANATION:  A  water  jacket  to  diminish  radiation.      B  —  Steel  bomb,  lined  with  enamel.     C  — 
Platinum  pan  for  coal.     D  —  Calorimeter  containing  weighed  water.     E — Electrode.     F  —  Fuse  wire.     G 
— Support  for  agitator  and  thermometer.     K — Spring  and  screw  for  revolving  agitator.     L — Lever  of 
agitator.       M  —  Pressure  gauge.       O  —  Oxygen  cylinder.       P — Electric   battery.       S  —  Agitator.      T- 
Thermometer. 

the  same  temperature  and  begins  to  cool,  and  the  rate  of  cooling  is  established.  The 
thermometer  used  is  graded  in  fiftieths  of  a  degree  centigrade,  and  can  be  read  to 
one-half  of  a  icoth  of  a  degree.  In  this  way  the  loss  through  radiation  during  com- 
bustion may  readily  be  determined  and  the  proper  allowance  made.  The  combustion  is 
always  complete  and  no  loss  of  heat  occurs  from  escaping  gases,  because  no  gases  escape 
until  the  operation  is  completed  and  the  bomb  opened.  An  illustration  of  this  calo- 
rimeter is  given  in  Fig.  i. 

In  a  power  plant  it  is  of  prime  importance  that  the  thermal  value  of  the  fuel  should 
be  known,  because  the  whole  efficiency  of  the  plant  is  affected  thereby.     The  coal,  as 


COMBUSTION.  113 

far  as  possible,  should  be  purchased  on  the  basis  of  the  heat  units  contained,  and  when 
possible  the  contractor  should  be  tied  down  to  a  standard  value,  a  deduction  being 
made  for  shipments  which  do  not  reach  the  guaranteed  value,  and  a  premium  being 
paid  for  excess  heat  units. 

The  method  of  sampling  the  coal  should  be  by  taking  a  small  portion  from  each 
filling  of  the  weighing  hopper.  These  samples  should  be  quartered  and  mixed  and 
a  final  sample  should  be  obtained  to  represent  the  average  value  of  the  shipment. 
Where  the  size  of  the  plant  warrants  it,  the  most  practical  method  of  sampling  the  coal 
is  by  means  of  an  automatic  sampling  machine,  such  as  is  used  in  the  large  smelters 
and  refineries  throughout  the  world.  The  final  sample  is  pulverized  and  tested  for  its 
heat  value  in  the  bomb  calorimeter,  after  which  approximate  analysis  is  made  of 
another  portion  of  the  sample.  This  method  of  purchasing  coal  has  been  successfully 
used  for  several  years  in  large  power  plants. 

In  the  boiler  room  it  is  desirable  to  keep  account  of  the  amount  of  coal  burned  in 
each  boiler,  and  likewise  of  the  firemen  handling  this  coal,  and  it  will  frequently  be 
found  that  an  increase  of  economy  can  be  secured  by  offering  premiums  for  the  small- 
est fuel  consumption.  These  premiums  offer  an  incentive  to  the  fireman  to  study  the 
conditions  under  which  coal  is  burnt  and  thereby  to  increase  his  efficiency,  contribut- 
ing greatly  to  the  reduction  of  the  fuel  bill.  In  continental  Europe  many  firemen 
have  to  serve  a  certain  apprenticeship  at  a  training  school  for  firemen,  and  such  men 
have  no  difficulty  in  securing  higher  wages  than  untrained  firemen. 

COMBUSTION. 

Combustion.  —  Combustion  of  carbon  is  a  rapid  chemical  action,  or  union  of  carbon 
and  oxygen  forming  carbon  dioxide.  The  combustible  elements  in  coal  are  carbon, 
hydrogen  and  sulphur;  different  coals  contain  from  70  per  cent  to  95  per  cent  of  carbon 
(C),  from  i  per  cent  to  10  per  cent  of  hydrogen  (H),  from  0.4  per  cent  to  2  per  cent  of 
sulphur  (S),  from  i  per  cent  to  10  per  cent  of  water  (H2O),  and  from  i|  per  cent  to 
18  per  cent  of  ashes.  The  table,  Fig.  i,  given  below  gives  the  approximate  analyses 
of  the  heating  value  of  American  coals. 

Air  Required.  —  The  theoretical  amount  of  air  required  to  completely  consume  a 
pound  of  carbon,  which  may  also  be  taken  without  great  error  for  a  pound  of  com- 
bustible, is  12  pounds;  in  practice,  however,  with  natural  draft  from  25  to  30  pounds 
is  required,  while  with  artificial  draft  the  amount  of  air  may  be  decreased  to  18 
pounds,  about  50  per  cent  more  than  the  theoretical  amount.  The  reason  for  the 
large  increase  where  natural  draft  is  used  is  that  the  ordinary  chimney  does  not 
produce  draft  of  intensity  enough  to  penetrate  the  bed  of  the  fire;  to  obtain  the 
necessary  air  for  complete  combustion  an  excess  must  be  supplied.  This  excess 
passes  through  the  fire  unconsumed,  mingles  with  the  gases  of  combustion,  and  to  a 
certain  extent  cools  them.  With  artificial  draft  a  smaller  grate  and  heavier  fire  is 
used,  the  air  is  forced  through  every  portion  of  the  coal,  and  complete  chemical  action 


114  STEAM-ELECTRIC    POWER    PLANTS. 

TABLE  I.  — PROXIMATE  ANALYSES   AND   HEATING  VALUES   OF   AMERICAN   COALS. 


Moisture. 

ij 

a 

JU 

ts 
~°  i 

Fixed  Carbon. 

J 

Sulphur. 

H  . 
Ml 

*   b   rt 

i^  . 

s|| 

0)        17; 

1R| 
•3i.fi 

>  ~  u 

J  si 

^  t-t  ii?.ti 

Theoretical 
Evaporation 
Ibs.  water  from 
and  at  212°  per 
Ib.  combustible 

Anthracite. 
Northern  coal  field     

7.42 

4.78 

87.27 

8.20 

.73 

13,160 

5OO 

East  Middle  coal  field   .... 
West  Middle  coal  field  .... 
Southern  coal  field     

3-71 
3.16 
7.OO 

3.08 
3-72 
4.28 

86.40 
81.59 
83.81 

6.22 

10.65 
8.18 

.58 

•5° 
.64 

13,420 

12,840 
13,220 

3-44 
4-36 
4.8c 

14,900 
14,900 

I5-42 
I5-42 

Anthracite  from  one  mine. 
Egg   Screen  2^"—  if" 

88.49 

c.66 

Stove     ....   Screen  if"—  i^" 

83.67 

10.17 

Chestnut  .    .    .   Screen  i\"-  f" 

80.72 

12.67 

Pea    Screen    f"-  %" 

70-O5 

14.66 

Buckwheat   .    .   Screen    J"-  \" 

76.02 

16.62 

Semi-  A  nthracite. 
Loyal  sock  field    

1.30 

8.10 

87.74 

6.23 

1.67 

I3,O2O 

8.86 

I  C   COO 

Bernice  basin  

.6c 

0.40 

87.69 

C.74 

.01 

13,700 

10.08 

ic.  coo 

Semi-Bituminous. 
Broad  Top,  Pa  

.70 

iC.6i 

77.3O 

C.4O 

.00 

I4,82O 

17.60 

1  5  800 

16  36 

Clearfield  County,  Pa  

.76 

22.  C2 

71.82 

7.OO 

I4,OCO 

24.60 

ic,7oo 

l6  2C 

Cambria  County,  Pa  
Somerset  County,  Pa  

•94 
i.c8 

19.20 
16.42 

71.12 

7.04 
8.62 

1.70 
1.87 

14,45° 
I4,2OO 

22.71 
20.77 

I5,7°° 
i  c  800 

16.25 

16  36 

Cumberland,  Md  

I.OO 

I7.7O 

73.12 

7-71? 

•74 

I4,4OO 

IQ-70 

1C,  800 

16  36 

Pocahontas,  Va  

I.OO 

2  I.OO 

74.30 

3.03 

.c8 

IC.O7O 

22.  CO 

1C  7OO 

New  River,  W.Va  

.8c 

17.88 

77.64 

.27 

15,220 

i  c.8oo 

16  36 

Bituminous. 
Connellsville,  Pa  

1.26 

3O.I2 

50-6i 

8.23 

.78 

14,050 

74.O3 

I  C   3OO 

15  84 

Youghiogheny,  Pa  

I.O7 

36.5O 

co.o  5 

2.61 

KT 

14,450 

38.73 

15,000 

1C  C7 

Pittsburg,  Pa  

1.77 

35.QO 

52.21 

8.02 

i.  80 

13,410 

4I.6l 

14  800 

1C    72 

Jefferson  County,  Pa  

1.  21 

32.53 

6o.QO 

4.27 

I.OO 

14,770 

35.47 

I  C  2OO 

1C    7/1 

Middle  Kittanning  seam,  Pa.  . 
Upper  Freeport  seam,  Pa.  and  O. 
Thacker,  W.Va  

1.81 

i-93 
1.78 

35-33 
35-9° 

7C.O4 

53-7° 
50.19 

C.6.O7 

7.18 

9.10 

6.27 

1.98 
2.89 
1.28 

13,200 
14,040 

40.27 

43-59 
30.33 

14,500 
I4,80O 
I  C.2OO 

15.01 

I5-32 
1C  1± 

7.87 

72.O7 

C7.6o 

6.50 

13,000 

3C.76 

14,600 

1C  II 

Brier  Hill,  O  

4.80 

74.6O 

4.30 

13,010 

38.20 

TA   7OO 

14  80 

Hocking  Valley,  O  

6.  co 

74.07 

48.85 

8.00 

i.  59 

12,130 

42.81 

I4,2OO 

14  7O 

Vanderpool,  Ky  

4.00 

74.IO 

C4.6o 

7-3° 

12,770 

38.  co 

14,400 

Id  OI 

Muhlenberg  County,  Ky   .    .    . 
Scott  County,  Tenn  

4-33 
1.26 

33-65 
35-76 

55-5° 

C7.I4 

4-95 

8.02 

i-57 
180 

I3>O6O 
13,700 

38.86 

34-17 

I4,40o(  ?) 
ic,ioo(  ?) 

14.91 
1C  67 

Jefferson  County,  Ala  

I.CC 

34-44 

59.77 

2.62 

1.42 

I3,77O 

37.63 

I4,4OO(  ?) 

14.  OI 

Big  Muddy,  111  

7.  Co 

30.70 

53-80 

8.00 

12,420 

M.7OO 

1C  22 

Mt.  Olive,  111.     

I  I.OO 

35.65 

37.10 

13.00 

10,490 

47.OO 

13,800 

14.  2O 

Streator,  111  

I2.OO 

33.30 

40.70 

14.00 

10,580 

45.OO 

I4,3OO 

14.80 

Missouri   

6.44 

47-94 

8.oc 

12,230 

43.Q4 

I4,3Oof  ?^ 

14.80 

Lignites  and  Lignitic  Coals. 
Iowa      

8-45 

37.09 

35.60 

1  8.86 

8,720 

5I.O3 

I2,OOo(  ?) 

12.42 

Wyoming      

8.19 

78.72 

41.87 

11.26 

10,  300 

48.O7 

I2,OOOf  ?) 

13  3C 

Utah      

0-2Q 

41.97 

44-37 

3.20 

T.T8 

48.60 

I2,000(?) 

I3.O4 

Oregon  Lignite    

15.25 

42.08 

77.72 

7.11 

1.66 

8,540 

C4.QC 

n,ooo(  ?) 

1  1.  3O 

By  courtesy  of  the  Babcock  &  Wilcox  Co. 


COMBUSTION. 


takes  place,  the  oxygen  being  more  fully  consumed.  In  other  words,  in  the  latter  case 
the  force  is  more  concentrated  than  in  the  former  and  the  work  performed  more 
effectively.  The  greater  the  percentage  of  carbon  dioxide  (CO2)  contained  in  the 


60| 


61 


I 

1  I 

6°  io|o0  tdo"  jio* 

FIG.  2.    Fuel  Loss  in  Flue  Gases. 

flue  gas  the  greater  the  efficiency.  A  chart  shown  in  Fig.  2  gives  the  percentage  of 
carbon  dioxide  for  various  chimney  temperatures,  and  the  resultant  percentage  of  fuel 
loss  is  indicated  at  the  left-hand  side  of  the  chart.  The  diagonal  lines  show  the  per- 
centage of  carbon  dioxide,  and  chimney  temperatures  are  given  at  the  bottom  in  Fahren- 
heit and  centigrade  degrees. 

C02  Recorder.  —  A  valuable  instrument  for  a  power  plant,  which  is  at  present 
much  in  use,  is  the  CO2  or  gas  composimeter,  which  enables  a  record  to  be  kept  of 


n6 


STEAM-ELECTRIC    POWER    PLANTS. 


Fir;.  3.     Ados  (Sarco)  CO2  Recorder,  Water  Motor 
Type. 

an  aspirator  Q,  fixed  to  the  top  of  the  instrument 
The  power  required  to  procure  and  deal  with 


the  percentage  of  carbon  dioxide 
in  the  chimney  gases.  It  may  be 
advantageous  to  the  fireman  to 
arrange  this  apparatus  so  that  he 
can  observe  the  movements  of  the 
needle  and  govern  his  fire  accord- 
ingly; it  being  generally  found 
that  a  fireman  can  be  taught  to 
read  this  instrument  with  but  a 
slight  amount  of  instruction. 
There  are  several  different  instru- 
ments on  the  market  for  this 
purpose,  such  as  the 

Arndt  Econometer. 

Cnstodis  Gas  Balance. 

Uchling  Gas  Compometer. 

Ados  or  Sarco  Carbon  Dioxide  Recorder. 

Simmance  &  Abadil  CO 2  Recorder. 

The  Arndt  apparatus  is  used 
when  a  complete  analysis  of  the 
gas  is  to  be  made.  The  Uehling 
and  the  Ados  apparatus  give  a 
continuous  record  on  a  strip  of 
paper,  as  does  also  the  Simmance 
&  Abadil,  while  the  other  instru- 
ments are  not  so  arranged,  being 
more  suited  for  laboratory  work. 
The  Ados  (Sarco)  apparatus  is 
shown  in  Fig.  3. 

These  recorders  are  frequently 
used  in  power  plants  and  give 
satisfactory  service.  The  opera- 
tion of  the  instrument  is  as  fol- 
lows : 

A  f-inch  pipe,  which  taps  the 
side  flue  or  last  combustion 
chamber  of  each  boiler,  is  con- 
nected to  the  inlet  pipe  D  of 
the  instrument  and  the  gas  is 
drawn  through  the  machine  by 
by  means  of  standard  T. 
the  gas  samples  is  derived  from  a 


COMBUSTION.  117 

fine  stream  of  water  at  a  head  of  about  2  to  3  feet;  6  to  8  gallons  are  required  per  hour 
(according  to  the  speed  at  which  the  machine  is  operated).  After  actuating  ejector  Q, 
a  portion  of  the  water  flows  to  the  small  tank  L,  which  serves  as  a  pressure  regulator, 
and  is  provided  with  an  overflow  tube  R.  From  this  tank  the  water  enters  tube  H  in 
a  fine  stream,  the  strength  of  which  is  adjusted  by  the  cock  S  (according  to  the  number 
of  records  that  may  be  desired  per  hour),  and  gradually  fills  the  vessel  K.  Vessel  K 
consists  of  an  upper  and  a  lower  compartment,  the  two  being  in  communication  with 
one  another  through  a  tube  erected  in  the  upper  chamber  and  reaching  nearly  to  the 
top  of  same.  The  water,  which  enters  this  vessel  K  through  the  tube  H,  gradually 
fills  the  upper  chamber  and  thus  compresses  the  air  contained  in  it.  This  pressure  is 
transmitted  to  the  lower  compartment  through  the  communication  tube  above  men- 
tioned, and  here  acts  upon  the  mixture  of  glycerine  and  water  (i  part  of  the  former 
to  3  of  the  latter)  with  which  this  is  filled,  driving  it  out  into  the  calibrated  tube  C. 
While  this  has  been  taking  place  the  aspirator  Q  has  been  drawing  a  continuous  stream 
of  gas  right  through  D,  C  and  E  in  the  direction  indicated  by  the  arrows.  When  the 
rising  liquid  in  C  has  reached  the  inlet  and  outlet  to  this  vessel,  no  further  gas  can 
enter  the  calibrated  tubes  for  the  moment,  and  the  aspirator  will  now  draw  the  gas 
through  the  seal  F,  and  out  in  the  direction  of  the  arrow  for  the  time  being.  Before 
the  liquid  can  close  the  center  tube  in  C,  the  gas  has  to  overcome  the  slight  resistance 
offered  by  the  elastic  bag  P,  and  is  thereby  forced  to  assume  atmospheric  pressure. 
The  moment  the  liquid  has  sealed  the  lower  open  end  of  this  center  tube,  exactly  100 
cub.  cm.  of  flue  gas  are  trapped  off  in  the  outer  vessel  C  and  its  companion  tube,  under 
atmospheric  pressure.  As  the  liquid  rises  farther,  the  gas  is  forced  through  the  thin 
tube  Z  and  into  vessel  A,  which  is  filled  with  a  solution  of  caustic  potash  at  1.27  specific 
gravity.  Upon  coming  into  contact  with  the  surface  of  the  potash  and  the  moistened 
sides  of  the  vessel,  the  gas  is  freed  from  any  carbon  dioxide  that  may  be  contained  in 
the  sample,  this  being  rapidly  and  completely  absorbed  by  the  potash.  The  remain- 
ing gas  gradually  displaces  the  potash  solution  in  A,  sending  it  up  into  vessel  B.  This 
has  an  outer  jacket,  filled  with  glycerine  and  supporting  a  float  N.  Through  the  center 
of  this  float  reaches  a  thin  tube,  through  which  the  air  in  B  is  kept  at  atmospheric  pres- 
sure. The  float  is  suspended  from  the  pen  gear  M  by  a  silk  cord  and  counterbalanced 
by  the  weights  X.  The  rising  liquid  in  B  first  forces  a  portion  of  the  air  therein  out 
through  the  center  tube  in  the  float,  and  then  raises  the  latter.  This  causes  the  pen 
lever  to  swing  upwards,  carrying  pen  Y  with  it. 

The  mechanism  is  so  calibrated  and  adjusted  that  the  pen  will  travel  right  to  the 
top,  or  zero  line  on  the  chart  when  only  atmospheric  air  is  passing  through  the  machine 
and  nothing  is  absorbed  by  the  potash  in  A. 

Thus,  should  any  carbon  dioxide  be  contained  in  the  gas  sample,  it  would  be  ab- 
sorbed by  the  potash  in  A,  not  so  much  of  this  liquid  would  be  forced  up  into  vessel  B 
and  the  float  would  not  cause  the  pen  to  travel  up  so  high  on  the  chart,  in  exact  accord- 
ance with  the  amount  of  CO2  absorbed.  The  tops  of  the  vertical  lines  recorded  on  the 
chart,  therefore,  provide  a  continuous  curve  showing  the  percentage  of  CO2  contained  in 
the  exit  gases  from  the  flues,  on  a  permanent  diagram  arranged  for  twenty-four  hours. 


u8 


STEAM-ELECTRIC    POWER    PLANTS. 


w 

GENERAL  CROSS  SECTION 


Extension  of  Municipal  Light  and  Power  Plant  at  Belfast,  Ireland. 


DRAFT.  119 

When  the  liquid  in  C  has  reached  the  mark  on  the  narrow  neck  of  that  tube,  the 
whole  of  the  100  cub.  cm.  have  been  forced  on  to  the  surface  of  the  potash,  one 
analysis  being  thus  complete.  At  this  moment  the  power  water,  which  simultane- 
ously with  rising  in  tube  H  has  also  traveled  upwards  in  siphon  G,  will  have  reached 
the  top  of  this  siphon,  which  then  commences  to  flow. 

Through  siphon  G  a  much  larger  quantity  of  water  is  disposed  of  than  flows  in 
through  cock  S,  so  that  the  power  vessel  K  is  rapidly  emptied  again. 

The  moment  the  pressure  on  this  vessel  is  released,  the  liquid  from  C  returns  into 
the  lower  compartment,  and  float  N  to  its  original  position. 

As  soon  as  the  liquid  in  C  has  fallen  below  the  gas-inlet  and  gas-outlet  to  this  vessel, 
the  whole  of  the  remaining  gas  is  rapidly  sucked  out  through  E  by  the  ejector  Q. 


DRAFT. 

Meaning.  —  The  word  "draft"  has  a  double  meaning,  and  as  a  result  there  is 
some  confusion ;  in  regard  to  combustion  it  only  refers  to  the  difference  in  air-pressure 
between  the  ash  pit  and  the  furnace  chamber,  while,  when  considered  on  a  broader 
basis,  it  refers  to  the  total  intensity  of  the  draft  or  difference  in  pressure  existing  between 
the  external  air  and  the  interior  of  the  boiler  setting.  This  intensity  may  be  measured 
at  a  number  of  points,  therefore,  unless  the  position  of  the  draft  gauge  is  specified, 
the  value  of  any  tables  referring  to  this  subject  are  greatly  reduced.  The  boiler  maker 
is  very  careful  in  his  guarantee  to  specify  the  draft  required  at  the  boiler  outlet,  and 
the  stoker  manufacturer  requires  a  certain  draft  intensity  at  the  bridge  wall,  the  chimney 
builder  will  specify  the  draft  generated  with  flue  gases  of  a  certain  temperature  when 
the  barometer  is  normal,  and  may  require  other  conditional  qualifications;  the  builder 
of  fans  will  guarantee  the  pressure  at  the  fan  outlet  for  forced  draft  and  the  vacuum 
at  the  fan  inlet  for  induced  draft.  From  this  it  will  be  seen  that  the  designer  of 
the  power  plant  has  the  difficult  problem  of  so  arranging  the  necessary  flues  and  con- 
duits that  a  harmonious  result  is  secured  at  the  lowest  first  cost  and  expense  of 
maintenance.  Each  case  must  be  judged  entirely  on  its  own  merits  and  requires 
considerable  knowledge  of  what  has  been  done,  and  what  is  feasible  on  the  part 
of  the  man  responsible  for  the  results,  for  a  decision  must  be  made  at  a  very  early 
stage  in  the  design  of  the  plant  in  regard  to  the  method  to  be  used;  an  error  of 
judgment  in  this  regard  will,  if  the  draft  is  insufficient,  necessitate  expensive  changes 
and  alterations  after  the  plant  is  in  operation,  and  the  installation  of  any  artificial 
draft- apparatus  at  this  time  will  be  greatly  hampered  in  design  by  the  existing 
structure,  and  therefore  undesirable  in  many  ways.  In  some  cases  it  will  be  found  that 
the  draft  intensity  provided  is  too  great,  and  while  this  is  a  fault  insomuch  as  it  shows 
that  a  greater  investment  has  been  made  than  the  case  justified,  it  is  better  to  err  on 
this  side,  but  care  must  be  used  in  order  that  too  great  an  error  is  not  made.  The 
prevailing  complaint  in  most  plants  is  "lack  of  draft,"  and  a  large  number  of  devices 
have  been  invented  and  put  in  use  for  supplying  the  deficiency. 


120 


STEAM-ELECTRIC   POWER   PLANTS. 


Draft  is  either  measured  in  inches  or  ounces.     The  following  Table  I,  gives  the 
corresponding  pressures  in  inches  and  ounces: 


TABLE  I. 


TZ  inch  =  .018  ounce 

|  inch      =     .363  ounce 

TS       ' 

=   .036 

f     "         =      .436 

J     ' 

=   .072 

I     "         =      -508 

1%     ' 

=   .109 

i       "         =     .581 

i    ' 

=   -145 

i\  inches  =     .726 

A    « 

3 

4    "      =    .872 

5      * 

=   .218 

if    "      =  1.017 

' 

=   .290 

2           "            =    I.l62       " 

Production.  —  There  are  several  methods  of  producing  draft:  the  chimney,  fans 
for  forced  or  induced  draft,  and  steam  jet  blowers  in  a  variety  of  applications. 

The  chimney  is  the  oldest  method  of  producing  draft  and  acts  by  the  difference 
in  weight  between  the  column  of  hot  gases  in  the  shaft,  and  that  of  an  equal  column 
of  atmospheric  air;  a  reduced  pressure  is  produced  at  the  base  of  the  stack,  in  the  flues 
and  boiler-setting,  allowing  air  to  flow  in  through  the  burning  coal  on  the  grate  from 
the  heavier  external  atmosphere. 

Induced  draft  is  similar  to  chimney  draft,  except  that  a  fan  or  other  means  is  used 
to  produce  the  draft. 

Forced  draft  may  be  on  either  of  two  systems,  the  closed  fire  room  which  is  generally 
found  on  the  ships,  and  the  closed  ash-pit  system  which  is  usually  found  in  power  plants. 
In  either  case  the  air  under  pressure  is  admitted  to  the  lower  side  of  the  grate  and 
passes  through  the  fire. 

Loss.  — The  average  loss  of  draft  in  a  water-tube  boiler  between  the  furnace  and 
the  flue  outlet  at  the  boiler  wall  is  0.20  inch  of  water  approximately;  the  data  refers 
to  the  regular  Babcock  &  Wilcox  or  Stirling  boiler.  This  loss  varies  according  to  the 
design  of  boiler  used  and  the  method  of  forcing,  but  a  common  allowance  to  cover  this 
loss  is  0.25  to  0.50  inch  of  water,  the  latter  when  the  boilers  are  forced,  and  the  balance 
of  the  draft  specified  by  the  boiler  maker  is  required  to  pass  the  air  through  the  grate 
and  fire.  One  prominent  builder  of  water-tube  boilers  calls  for  from  0.50  to  0.70  inch 
of  water  at  the  boiler  flue  outlet,  with  semi-bituminous  coal  and  boilers  operated  at 
their  normal  capacity,  and  a  larger  draft  pressure  is  required  should  the  boilers  be 
forced.  The  kind  of  fuel  to  be  burned  must  also  be  considered ;  for  instance,  the  small 
sizes  of  anthracite  coal  require  a  high  draft  intensity,  and  with  stokers,  for  the  same 
kind  of  coal,  it  will  require  a  greater  intensity  of  draft  to  burn  the  same  quantity  of  coal 
per  square  foot  of  grate  than  is  required  for  hand  firing. 

The  design  of  the  smoke  flues  or  boiler  breechings  has  a  considerable  influence  on 
the  draft  intensity  available,  and  there  is  comparatively  little  accurate  data  on  the 


DRAFT. 


121 


subject.  Square  flues  are  not  as  efficient  as  circular  flues,  but  the  exigencies  of  con- 
struction usually  require  the  adoption  of  rectangular  flues.  The  losses  in  flues  are 
due  to  the  friction  and  leakage.  Right-angled  bends  are  productive  of  considerable 
loss  of  draft.  A  convenient  "rule  of  thumb"  allows  0.15  inch  draft  loss  per  hundred 
feet  of  flue  and  0.075  incn  f°r  eacn  bend  when  circular  flues  are  used;  these  values 
are  doubled  for  brick  lined  flues  of  rectangular  section.  The  above,  of  course,  only 
applies  when  sufficient  flue  area  is  provided. 

Economizers  cause  a  considerable  loss  in  draft  (often  as  high  as  0.4  to  0.5  of  an 
inch),  and  it  is  usually  necessary  to  increase  the  height  of  the  chimney,  25  per  cent. 

The  unbalanced  pressure  due  to  the  difference  in  weight  between  the  hot  column 
of  gas  in  a  chimney  and  the  external  air  is  partially  absorbed  by  the  inertia  of  the  air, 
or  its  resistance  to  being  set  in  motion,  and  the  friction  in  the  chimney;  additional 
losses  may  be  caused  by  the  lack  of  proper  baffle  walls.  In  addition  the  chimney  must 
be  designed  to  supply  a  draft  of  sufficient  intensity  to  overcome  the  combined  resist- 
ance of  the  boiler,  grate,  flues  and  dampers,  and  it  must  be  able  to  supply  the  maxi- 
mum draft  requirements  under  the  most  unfavorable  conditions  of  the  barometer  and 
atmospheric  humidity.  The  quantity  of  coal  which  can  be  burned  on  a  grate  depends 
upon  the  quantity  of  air  which  can  be  forced  through  the  grate.  As  will  be  shown  in 
the  chapter  on  combustion,  the  latter  value  may  range  from  the  theoretical  amount 
of  air  required  to  50  per  cent  or  more  in  excess. 

Chimney  Draft.  —  The  following  Table  II,  gives  the  height  of  water  column  in 
inches,  due  to  the  unbalanced  pressure  in  a  chimney  100  feet  high  for  various  tem- 
peratures of  the  external  air  and  hot  gases.  As  the  draft  intensity  varies  directly  with 
the  height  of  the  chimney,  the  intensity  of  draft  due  to  higher  or  lower  chimney  can  be 
found  by  proportion. 

TABLE  II.   —  HEIGHT  OF  WATER  COLUMN  DUE  TO  UNBALANCED  PRESSURES 
IN  CHIMNEY  100  FEET  HIGH.* 


Temperature 
in  Chimney. 

TEMPERATURE  OF  EXTERNAL  AIR.     BAROMETER  14.7  Lws.  PER  SQUARE  INCH. 

0° 

10° 

20° 

3°° 

40° 

50° 

60° 

7°° 

80° 

90° 

100° 

200° 

•453 

.419 

.384 

•353 

.321 

.292 

.263 

•234 

.209 

.182 

•157 

220° 

.488 

•453 

.419 

.388 

•355 

.326 

.298 

.269 

•244 

.217 

.192 

240° 

.520 

.488 

•45  * 

.421 

.388 

•359 

•33° 

.301 

.276 

.250 

.225 

260° 

•555 

.528 

•484 

•453 

.420 

•392 

•363 

•334 

•3°9 

.282 

•257 

280° 

•584 

•549 

•515 

.482 

•45  i 

.422 

•394 

•365 

•340 

•313 

.288 

300° 

.611 

•576 

•541 

•5" 

.478 

•449 

.420 

•392 

•367 

•340 

•315 

320° 

•637 

.603 

.568 

•538 

•5°5 

.476 

•447 

.419 

•394 

•367 

•342 

340° 

.662 

.638 

•593 

•563 

•53° 

.501 

•472 

•443 

.419 

•392 

•367 

360° 

.687 

•653 

.618 

.588 

•555 

.526 

•497 

.468 

•444 

.417 

•392 

380° 

.710 

.676 

.641 

.611 

•578 

•549 

.520 

.492 

.467 

.440 

•415 

400° 

•732 

.697 

.662 

.632 

•598 

•57° 

•541 

•5*3 

.488 

.461 

•436 

420° 

•753 

.718 

.684 

•653 

.620 

•591 

•563 

•534 

•5°9 

.482 

•457 

440° 

•774 

•739 

•7°5 

.674 

.641 

.612 

•584 

•555 

•53° 

•5°3 

.478 

460° 

•793 

•758 

.724 

.694 

.660 

.632 

.603. 

•574 

•549 

.522 

•497 

480° 

.810 

.776 

.741 

.710 

.678 

.649 

.620 

•591 

.566 

•540 

•5i5 

500° 

.829 

.791 

.760 

•73° 

.697 

.669 

•639 

.610 

.586 

•559 

•534 

*  "The  Locomotive,"  1884. 


122  STEAM-ELECTRIC   POWER   PLANTS. 

The  foregoing  table  emphasizes  the  value  of  high  chimney  temperatures  in  pro- 
ducing draft,  and  clearly  shows  the  reason  why  chimneys  act  better  in  cold  weather. 
In  practice  it  will  be  found  that  the  actual  draft  intensity  produced  is  lower  than  the 
computed  intensity,  owing  to  the  fact  that  friction  must  be  overcome  and  the  heat  of 
the  gases  decreases  as  they  approach  the  top  of  the  chimney. 

The  formula  used  in  computing  this  table  is : 

F  =  .192  H  (D  -  d] 
in  which 

F  =  Intensity  of  draft  in  inches  of  water. 

H  =  Height  of  chimney  in  feet. 

D  =  Density  of  external  air. 

d  —  Density  of  hot  gases. 
.192  =  A  factor  for  converting  pressure  in  Ib.  per  square  foot  to  inches  of  water. 

The  theoretical  velocity  of  the  gases  due  to  this  draft  intensity  can  be  computed 
by  the  following  formula: 

2g  XSooh 


v  =    — 

12 


in  which 

v  —  The  theoretical  velocity  in  feet  per  second. 

g  =  Gravity  (32.2). 

h  =  Head  in  inches  of  water. 

800  =  The  ratio  between  the  weight  of  equally  high  columns  of  water  and  the  flue 
gases  at  the  temperature  of  +  32°  F. 

In  using  this  formula  for  theoretical  accuracy  a  correction  factor  is  necessary  to 
cover  the  temperature  of  the  flue  gases,  but  owing  to  the  great  number  of  unknown 
factors  in  the  problem  as  it  exists  at  any  power  plant,  such  line  drawn  assumptions  are 
beside  the  mark,  and  the  formula  can  be  used  as  it  stands. 

Kent's  formula  for  the  area  of  a  chimney  is : 

0.06  X  W 

A  = ;= 

V  H 

in  which 

A  =  Area  of  chimney  in  square  feet. 
W  =  Total  fuel  consumption  in  pounds  per  hour. 
H  =  Height  of  chimney  in  feet. 

The  following  Table  III  from  Kent's  Pocket  Book  gives  the  size  of  chimney 
based  on  a  fuel  consumption  of  five  pounds  of  coal  per  horse-power  hour,  based  on 
the  commercial  horse-power  of  the  boilers,  and  a  similar  one,  Table  IV,  is  given,  based 
on  four  pounds  of  coal  per  horse-power  hour  from  Christie  on  "Chimney  Design." 


DRAFT. 


123 


TABLE  III.  —  KENT'S  TABLE  OF  SIZE  OF  CHIMNEYS  FOR  STEAM  BOILERS. 
Formula:  H.P.  =  3.33  (A  —  0.6  ^  A)  "»  H.     (Assuming  i  H.P.  =  5  Ibs.  of  coal  burned  perjiour.) 


Diameter, 
Inches. 

Area  A. 
Sq.  feet. 

Effective 
Area, 
E  = 
A  —  0.6  VA. 
Sq.  feet. 

HEIGHT  OF  CHIMNEY. 

Equivalent 
Square 
Chimnev. 
Side  of" 
Square, 
VE+4in. 

5°' 

60' 

70' 

So' 

90' 

100' 

no' 

I25' 

150' 

175' 

200' 

225' 

250' 

300' 

COMMERCIAL  HORSE-POWER  OF  BOILER. 

18 

21 

24 
27 

3° 

33 
36 
39 

42 
48 

54 
60 

66 

72 
78 
84 

90 
96 

102 

108 

114 

120 
132 
144 

1.77 
2.41 
3-H 
3-98 

4.91 

5-94 
7.07 
8.30 

9.62 

12.57 
15.90 
19.64 

23.76 
28.27 
33-i8 
38.48 

44.18 
50.27 

56.75 
63.62 

70.88 
78.54 
95-03 
113.10 

•97 
1.47 
2.08 
2.78 

3.58 
4.48 

5-47 
6-57 

7.76 
10.44 

13-51 
16.98 

20.83 
25.08 

29-73 
34.76 

40.19 
46.01 

52-23 
58.83 

65-83 

73-22 

89.18 

106.72 

23 
35 
49 
65 

84 

25 
38 

54 
72 

92 

"5 
141 

27 
4i 
58 
78 

100 

125 

152 
183 

216 

29 

44 
62 

83 

107 

!33 
163 
196 

231 
3" 

16 
*9 

22 
24 

27 

3° 

32 

35 

38 
43 
48 

54 

59 
64 
70 

75 

80 
86 

91 
96 

IOI 

107 
117 
128 

66 
88 

"3 
141 

173 
208 

245 
33° 
427 
536 

119 
149 
182 

219 

258 
348 

449 
565 

694 

835 

156 
191 
229 

271 

365 
472 

593 

728 
876 
1038 
1214 

204 
245 

289 
389 
5°3 
632 

776 
934 
1107 
1294 

1496 
1712 
1944 
2090 

268 

316 

426 

55i 
692 

849 

1023 

1212 
I4l8 

1639 
1876 
2130 
2399 

2685 
2986 

3637 
4352 

342 
460 

595 
748 

918 
1105 
1310 

i53i 

1770 
2027 
2300 
2592 

2900 
3226 

3929 
4701 

492 
636 
800 

981 
1181 
1400 
l637 

1893 
2167 

2459 
2771 

3100 
3448 
4200 
5026 

675 
848 

1040 
1253 
1485 
1736 

2008 
2298 
2609 
2939 

3288 
3657 
4455 
533,1 

894 

1097 
1320 

^65 
1830 

2116 
2423 
2750 
3098 

3466 

3855 
4696 
5618 

1201 
1447 

17*5 

2005 

2318 
2654 
3012 

3393 

3797 
4223 

5*44 
6i55 

For  pounds  of  coal  burned  per  hour  for  any  given  size  of  chimney,  multiply  the  figures  in  the  table  by  5. 

The  capacity  of  the  chimney  for  other  rates  of  fuel  consumption  is  easily  found 
from  these  tables  by  proportion,  as,  for  example,  in  Table  III,  where  a  coal  consump- 
tion of  5  pounds  per  boiler  horse-power  per  hour  has  been  assumed;  the  figures  given 
in  this  table  may  be  multiplied  by  the  ratio  of  5  to  the  maximum  expected  coal  con- 
sumption per  horse-power  hour.  Thus,  with  conditions  which  make  the  maximum 
coal  consumption  only  2.5  pounds,  the  chimney  300  feet  high  by  12  feet  diameter 
should  be  sufficient,  for  6,155  X  2  =  12,310  horse-power. 

A  table  showing  the  practice  of  several  prominent  plants  in  actual  operation,  and 
a  sufficient  amount  of  data  in  regard  to  their  equipment  to  enable  comparisons  to  be 
made,  is  given  in  Table  V. 


124 


STEAM-ELECTRIC   POWER   PLANTS. 


TABLE  IV.  —  CHRISTY'S  TABLE  OF  SIZE  OF  CHIMNEYS  FOR  STEAM  BOILERS. 
Formula:  H.P.  =  3.25  A^H.     (Assuming  i  H.P.  =  4  Ibs.  of  coal  burned  per  hour.) 


Diameter 

in 
Inches. 

Area 
(A) 
Sq.  feet. 

HEIGHT  OF  CHIMNEY. 

Equivalent 
Side  of 
Square 
Chimney 
in  Inches. 

50' 

60' 

70' 

80' 

90' 

100' 

no' 

125' 

150' 

175' 

200' 

225' 

250' 

300' 

COMMERCIAL  HORSE-POWER  OF  BOILER. 

18 

21 
24 
27 
3° 

33 
36 
39 

42 
48 

54 
60 
66 
72 
78 
84 
90 
96 

102 

108 

H4 
1  20 
132 
144 

1.77 
2.41 
3-14 
3-98 
4.91 

5-94 
7.07 
8.30 
9.62 

I2-57 
15.90 
19.64 
23.76 
28.27 
33-i8 
38-48 
44.18 
50.27 

56-75 
63.62 
70.88 
78.54 
95-03 
113.10 

42 
55 
72 
91 
114 

46 
62 

78 

101 

124 
149 
179 

49 
65 
85 
107 

J33 
163 
192 
224 
263 

52 
68 

91 
114 

i43 
172 
205 
241 
282 
364 

16 

J9 

22 

24 
27 
30 
32 

35 
38 
43 
48 

54 
59 
64 

70 

75 
80 
86 

91 
96 

101 

107 
117 
128 

98 
124 

I53 

182 
218 

257 
296 

387 

49  1 
605 

159 
192 
228 
270 
312 
410 
5i7 
637 
774 
920 

202 
241 
283 
332 
429 

543 
669 
809 
962 
1131 
1310 

257 
302 

351 
458 
579 
7i5 
865 
1051 
1206 
1401 
1609 
1830 
2067 
2314 

39° 

510 
647 

797 
965 
1147 

1349 
!563 
*794 
2041 
2304 
2584 
2879 
3*9l 
3861 

45<><> 

683 
845 

1021 
1215 

1459 
1654 
1898 

2161 

2434 
2734 

3°45 
3374 
4082 

4859 

1092 
1300 

1524 
1768 
2031 
2311 
2607 
2935 
3257 
3611 
4368 
5200 

1378 
1619 

1875 
2155 
2451 
2766 
3101 

3455 
3821 

4631 

55!5 

1706 
1976 
2269 
2584 
29J5 
3269 

3643 
4037 
4882 
5811 

2165 
2486 
2831 
3i95 

3578 

399  1 
4420 

535° 
6367 

TABLE   V.  —CHIMNEY  DATA  OF  RECENT  POWER  PLANTS. 


Waterside  II, 
New  York. 

L  Street,  Boston. 

f  d 

i-,  e» 
</:  S 

•#£ 
£ 

1-    •/   i_ 

O   i-    C 

S|> 

rl 

Chelsea,  London  . 

Twin  Municipal, 
Vienna. 

u 

<J~—  • 
rtQ 

5j3 

4 

Soth  Street, 
New  York. 

Height  of  chimney  above  grate  in  feet    .    .    . 

300* 

232 

205 

250 

253*t 

205 

,s5 

225    t 

Diameter  at  top  in  feet  

20 

16 

18 

I  c  ; 

10 

12.  =; 

12 

it 

Size  of  boiler  in  square  feet  

?2IO 

6060 

Number  of  boilers                    .    . 

16 

16 

2O 

8 

12 

Total  grate  surface  per  chimney  in  square  feet 

3024 

1760 

1600 

1344 

1660 

876 

880 

I2OO 

Ratio  of  chimney  to  grate      

1:9.63 

i  :8.O4 

1:6.3 

1:7.15 

1:5.89 

1:7.18 

1:7.78 

i:6.25 

*  Above  lower  grates. 


t  Economizer. 


DRAFT. 


125 


The  practice  of  proportioning  a  chimney  according  to  the  nominal  horse-power  of 
the  boiler  is  peculiar  to  the  United  States  alone;  in  Europe  a  more  scientific  analysis 
of  the  problem  is  used,  but  it  is  doubtful  if  the  results  attained  are  any  more  satisfac- 
tory than  the  more  simple  method  used  in  America,  owing  to  the  large  number  of 
unknown  quantities  involved,  and  it  is  extremely  doubtful  whether  the  subject  will 
ever  be  covered  by  a  simple  rational  formula. 

The  efficiency  of  the  chimney  considered  as  a  machine  for  the  production  of  draft 
is  low.  The  movement  of  the  air  depends  upon  the  heating  of  the  air,  but  its  actual 
movement  must  be  considered  entirely  upon  mechanical  principles,  and  the  heat  car- 
ried off  by  the  escaping  gases  is  absolutely  wasted,  so  far  as  its  utilization  for  any  other 
purpose  is  concerned ;  that  is,  any  attempt  to  extract  heat  from  the  gases  leaving  the 
boiler  will  result  in  a  reduction  of  the  draft.  This  loss  is,  therefore,  always  chargeable 
to  the  use  of  a  chimney  for  the  production  of  draft.  The  following  Table  VI,  taken 
from  "A  Treatise  on  Mechanical  Draft,"  issued  by  the  B.  F.  Sturtevant  Co.  of  Boston, 
Mass.,  shows  the  number  of  heat  units  carried  off  by  escaping  gases  at  different  in- 
creases of  temperature  above  that  of  the  atmosphere,  and  varying  excess  of  air  supply 
over  that  theoretically  required  for  complete  combustion.  It  will  be  noted  that  these 
losses  are  of  considerable  magnitude.  With  coal  having  a  thermal  value  of  11,720 
B.T.U.  per  pound  and  an  air  supply  100  per  cent  in  excess  of  the  theoretical  require- 
ment, the  percentage  of  heat  lost  will  vary  from  11.4  per  cent  with  the  escaping  gases 
at  300°  Fahr.  above  that  of  the  atmosphere  to  20.9  per  cent  when  the  difference  in 
temperature  is  500°  Fahr. 


TABLE  VI. —  SHOWING  B.T.U.  CARRIED  OFF  BY  ESCAPING  GASES  AT  VARIOUS 
TEMPERATURES  ABOVE  THAT  OF  THE    ATMOSPHERE  AND  VARIOUS 
EXCESS    AIR    SUPPLY. 


TEMPERATURE  OF  WASTE  GASES  ABOVE  THAT  OF  ATMOSPHERE. 

Excess  of  Air  in 

per  cent. 

300° 

35°° 

B.T.U. 

45°° 

500° 

55°° 

0 

695 

812 

928 

1,044 

1,160 

1,276 

5o 

1,016 

1,185 

i,354 

i,524 

I>693 

1,862 

75 

1,176 

i,372 

1,568 

1,764 

i,959 

2,i55 

IOO 

i,336 

i,558 

1,781 

2,003 

2,226 

2,448 

125 

i,495 

i,745 

1,994 

2,243 

2,492 

2,742 

*S° 

i,655 

i,93i 

2,207 

2,483 

2,759 

3,035 

175 

1,815 

2,118 

2,420 

2,715 

3,025 

3,328 

200 

i,975 

2,304 

2,633 

2,975 

3,291 

3,621 

The  efficiency  of  the  chimney  can  be  determined  by  the  computation  of  the- number  of 
foot  pounds  required  to  produce  the  movement  of  the  air  or  gases  as  compared  with  the 
foot  pounds  represented  by  the  amount  of  heat  expended  in  producing  that  movement. 
For  example,  assuming  a  chimney  100  feet  high  having  an  area  of  10  square  feet,  the 
atmosphere  at  a  temperature  of  +  62°  Fahr.  and  the  chimney  gases  at  +  500°  Fahr. 


126  STEAM-ELECTRIC  POWER  PLANTS. 

For  the  sake  of  simplicity  it  is  assumed  that  no  work  is  lost  in  friction  and  that  heated 
air  is  substituted  for  the  hot  gases,  their  density  and  specific  heat  being  approximately 
the  same.  Under  these  conditions  the  pressure  difference  at  the  base  of  the  chimney 
will  be  found  as  follows: 

p  =  h  (d  -  d'} 
in  which 

p  —  the  difference  in  pressure  at  base  of  chimney. 
h  =  loofeet  =  height  of  chimney  in  feet. 

d  =  0.0761  =  the  weight  of  one  cubic  foot  of  air  at  a  temperature  of  4-  62°  Fahr. 
d'  =  0.0414  =  the  weight  of  one  cubic  foot  of  air  at  a  temperature  of  +  500°  Fahr. 

Hence 

p  =  100  (0.0761  —  0.0414)  =  3.47  pounds  per  square  foot. 

The  height  of  the  column  of  external  air  which  will  produce  the  above  pressure  per 
square  foot  is 


Substituting  the  values  in  this  formula  and  solving: 


70.0761  —  o.o4i4\ 
H  =  100  -  I  =45.6  feet. 

\       0.0761       / 

The  velocity  of  the  air  entering  the  chimney  under  this  head  will  be : 

v  =  V  2gH  =  V  64.32  X  45.6  =  54.2  feet  per  second. 
The  weight  of  air  moved  per  second  will  be: 

Weight  =  54.2  X  0.0761  X    10  =  41.25  pounds. 

In  this  computation  10  =  the  area  of  the  chimney  in  square  feet.  The  movement  of 
this  air  is  the  result  of  heating  it  from  +62°  to  +500°,  that  is  through  500°  —  62°  = 
438°  Fahr.  As  the  specific  heat  of  air  under  a  constant  pressure  is  0.237,  the  total 
heat  expended  per  second  in  moving  41.25  pounds  will  be: 

Heat  expended  =  41.25  X  438  X  0.237  =  4,291  B.T.U. 

As  one  heat  unit  is  equivalent  to  778  foot  pounds,  the  energy  equivalent  of  the  above 
amount  of  heat  is: 

Energy  equivalent  of  heat  =  4,291  X  778  =  3,338,398  foot  pounds. 


DRAFT.  127 

The  work  actually  done  is  the  result  of  overcoming  a  pressure  of  3.47  pounds  per  square 
foot  over  an  area  of  10  square  feet,  through  a  distance  of  54.2  feet;  that  is, 

Actual  work  =  3.47  X  10  X  54.2  =  1,881  foot  pounds. 
And  the  efficiency  of  the  chimney  is: 

i  88  1 
Efficiency  =   -          -5-  =  0.000563  =  0.0563  per  cent. 


In  actual  practice  the  efficiency  of  the  chimney  is  much  lower  than  this  figure,  owing 
to  the  cooling  of  the  gases,  friction  and  other  causes. 

Mechanical  Draft.  —  Mechanical  draft  may  be  either  forced  or  induced  ;  forced 
draft  is  created  by  forcing  air  under  the  grates,  while  induced  draft  is  created  by  re- 
moving the  gases  of  combustion,  by  a  mechanical  device,  after  they  leave  the  boiler, 
thus  producing  a  partial  vacuum  in  the  furnace  and  drawing  air  through  the  grates. 

Mechanical  draft,  either  forced  or  induced,  possesses  the  advantage  that  it  is  under 
absolute  control  at  all  times,  can  be  forced  to  any  extent  within  reason,  and  is  indepen- 
dent of  atmospheric  conditions  which  affect  chimneys;  forced  draft  being  more  in  favor 
for  large  plants  than  the  induced  system.  The  disadvantage  of  mechanical  draft 
is  the  liability  to  fail  at  critical  moments.  This  can,  in  a  way,  be  guarded  against  by 
duplicate  installations,  but  such  precautions  are  not  infallible.  The  chimney,  on 
the  other  hand,  depends  upon  the  ever-acting  force  of  gravity,  and  so  long  as  a  fire  can 
burn  a  certain  amount  of  draft  will  be  secured.  The  chimney,  however,  cannot  be 
forced,  it  must  be  built  large  enough  at  the  start,  the  draft  can  be  reduced  if  excessive 
by  dampers,  but  if  not  sufficient  the  only  recourse  is  to  reinforce  it  by  mechanical 
methods. 

Another  great  advantage  in  the  use  of  mechanical  draft  is  the  low  grade  of  coal 
that  may  be  efficiently  burned,  and  its  adaptability  to  sudden  calls  for  steam  as  required 
in  power  plants. 

Regarding  first  cost,  the  blower  installation  may  be  much  cheaper  than  natural  draft; 
this  depends,  however,  on  the  design  of  the  plant,  the  operating  expense  of  a  blower 
when  steam  driven  is  about  i  per  cent  to  2  per  cent  of  the  total  steam  output. 
This,  however,  should  not  be  considered,  for  the  exhaust  steam  can  be  utilized, 
while  the  more  economical  combustion  will  outweigh  this  additional  expense. 

Forced  Draft.  —  Forced  draft  on  the  closed  ash  pit  is  practically  the  only  available 
method  for  use  in  power  plants,  as  the  closed  fire-room  system  is  out  of  the  question, 
unless  very  expensive  construction  is  adopted.  With  forced  draft  there  is  practically 
no  limit  to  the  amount  of  fuel  which  may  be  burned  by  forcing  the  system  to  its  utmost, 
but  such  measures  are  not  desirable  for  economical  reasons.  The  fan  is  usually  of 
sufficient  size  to  supply  a  number  of  boilers.  The  air  is  drawn  from  the  boiler  room, 
thus  assisting  ventilation,  and  carried  through  ducts  under  the  floor  to  each  ash  pit. 
The  air  ducts  must  be  air-tight  and  with  as  few  bends  as  possible,  in  order  to  reduce 


128  STEAM-ELECTRIC   POWER   PLANTS. 

leakage  and  friction.  The  total  area  of  all  branch  outlets  should  be  about  50  per  cent 
larger  than  that  of  the  main  duct.  The  efflux  of  the  air  into  the  ash  pit  is  controlled 
by  suitable  dampers  or  gates  so  arranged  as  to  prevent  ashes  from  falling  into  the 
openings.  The  common  mistake  of  placing  the  air  inlets  on  one  side  of  the  ash 
pits  only  results  in  intense  local  combustion  on  the  grates  at  certain  points,  and  a  com- 
paratively dead  fire  at  others.  It  is  better  to  introduce  the  air  at  the  front  and  back 
as  well  as  on  the  sides;  better  distribution  can  thus  be  insured.  In  many  cases  the 
above  troubles  are  not  discovered  or  realized  until  after  the  plant  is  in  operation,  and 
frequently  this  system  is  installed  to  help  out  insufficient  chimney  capacity.  The 
bridge  wall  is  usually  not  used  for  an  inlet  until  the  above-mentioned  troubles  have 
made  themselves  manifest. 

The  fan  or  blower  capacity  depends  on  the  total  quantity  of  fuel  to  be  burned  in 
all  the  grates,  and  an  excess  should  be  allowed  to  permit  forcing  the  boilers.  The 
air  pressure  depends  upon  the  kind  of  fuel  to  be  used  and  duct  friction  to  be  overcome; 
it  is  advisable  to  assume  that  the  fan  can  deliver  to  the  ash  pits  its  full  volume  at  2  inches 
of  water  pressure,  the  fan  should  be  able  to  deliver  to  the  ducts  at  a  pressure  of  3.5  inches 
of  water  or  two  ounces  per  square  inch,  but  this,  of  course,  depends  on  the  ducts  and 
the  general  arrangement  of  the  plant. 

An  advantage  of  forced  draft  over  the  induced  draft  system  is  that  the  air 
supplied  by  the  fan  is  comparatively  cool,  and  therefore  the  volume  swept  by  the  fan 
is  smaller.  The  disadvantage  arises  from  the  complicated  duct  system  required,  and 
the  power  required  to  force  the  air  through  them;  in  many  cases  there  is  scant  room 
to  put  in  ducts,  and  highly  undesirable  expedients  have  to  be  adopted  to  get  the  instal- 
lation in. 

Induced  Draft.—  Induced  draft  is  similar,  as  pertains  to  the  main  portion  of  the 
plant,  to  chimney  draft,  and  fans  or  steam  blowers  may  be  used.  Steam  blowers  or 
ejectors  are  used  to  reinforce  chimney  draft,  being  installed  in  the  base  of  the  stack. 
Such  blowers  are  only  suited  to  small  chimneys,  as  previously  mentioned,  and  are  not 
economical.  Induced  draft  fans  are  used  in  many  cases  with  success,  the  chimney 
being  reduced  to  a  stub  of  only  sufficient  height  to  reject  the  hot  gases  and  smoke  clear 
of  the  buildings.  The  height  of  the  stack  is  governed,  for  induced  draft,  by  the  demand 
for  operating  the  plant  so  that  it  will  not  be  a  nuisance  to  the  neighborhood,  the 
actual  requirements  in  this  line  being  merely  a  discharge  from  the  fan.  A  duplicate 
fan  is  installed  in  order  to  insure  continuity  of  operation,  but  such  precautions  are 
seldom  found  necessary.  Induced  draft  plants  are  usually  employed  in  connection 
with  economizers;  this  cools  the  gases  somewhat,  but  at  the  same  time  there  is  con- 
siderable air  leakage  in  the  boiler  and  economizer  settings,  which  are  usually  built  of 
brickwork,  this  must  also  pass  through  the  fans.  The  fan  must  be  of  sufficient 
capacity  to  deal  with  the  hot  gases  with  a  margin  of  safety,  and  capable  of  pro- 
ducing a  vacuum  of  about  1.5  inches  of  water  at  the  bridge  wall,  dependent,  of 
course,  on  the  fuel  to  be  used  and  the  amount  of  forcing  to  which  the  boilers  will  be 
subjected.  In  addition,  the  flue  and  economizer  friction  must  be  overcome  and  suffi- 


DRAFT. 


129 


cient  pressure  generated  to  discharge  the  gases  freely  into  the  air;  this  usually  calls 
for  a  suction  equivalent  to  about  2.50  inches  of  water  at  the  fan  when  economizers  are 
used,  but  owing  to  the  fact  that  each  installation  possesses  features  peculiar  to  itself 
it  is  not  advisable  to  give  fixed  data. 

The  advantage  of  induced  draft  over  forced  draft  is  that  it  does  not  require  any 
stack  to  carry  off  smoke :  in  the  former  case  the  stack,  which  is  in  reality  only  a  delivery 

TABLE  VII.  —  WEIGHTS  OF  AIR,   VAPOR  OF  WATER,   AND   SATURATED  MIXTURES  OF 

AIR    AND    VAPOR.* 

At  Different  Temperatures  under  the  Ordinary  Atmospheric  Pressure  of  29.921  Inches  of  Mercury. 


t.  i 

MIXTURES  OF  AIR  SATURATED  WITH  VAPOR. 

0  S  Ji 

W 

<  §.E  8 

S  d  2  « 

"8  °  3 

WEIGHT  OF  CUBIC  FOOT  OF  THE 

a.  a  s 
rtjg  tg  4 

§  £ 

^  l"f  " 

u3§-§ 

4>j-5  I3 

C    <L.b   c    L.' 

MIXTURE  OF  AIR  AND  VAPOR. 

t9-s.tr 

&•£  ^ 

H  S 

G  **  **  bo 

C     Q 

i-  ^  a? 

jy  *5    ""  S 

S           t/5 

Q  'S  §.  03 

"0*0  o.  E 

<  9 
W  W 

"SO     a 

£-Stt! 

o.s  °  S.« 

-.S 

*S  0^2 

•3       « 

O  *^3    O  C 

<S-o>'e 

-    etf 

-"  "•!= 

u  a 

Etc  «oN 

•§5"°  S  [/•• 

IsJ 

.y<  H^«g 

•i^l 

•S*^  H  3 

•E'Bi8- 

•S'E  ° 

0          U 

S  E-.E 

Pa, 

>  s  rt  rt 

Ilil 

|^l  Sj 

||| 

h!'!J 

$1? 

|^^'£ 

3  I'- 

1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

ii 

0° 

•935 

.0864 

.044 

29.877 

.086? 

.000079 

.086379 

.OOO92 

1092.4 

12 

.960 

.0842 

.074 

29.849 

o 
.0840 

.000130 

.084130 

y 
.00155 

646.1 

22 

.980 

.0824 

29.803 

.0821 

.OOO2O2 

.082302 

.00245 

406.4 

32 

I.OOO 

.0807 

.l8l 

29.740 

.0802 

.000304 

.080504 

.00379 

263.81 

3289 

42 

I.O20 

.0791 

.267 

29.654 

.0784 

.000440 

.078840 

.00561 

178.18 

2252 

S2 

I.O4I 

.0776 

.388 

29-533 

.0766 

.000627 

.077227 

.00819 

122.17 

1595 

62 

1.061 

.0761 

•556 

29-365 

•0747 

.000881 

•075581 

.01179 

84.79 

"35 

72 

1.082 

.0747 

.785 

29.136 

.0727 

.OO  I  22  I 

.073921 

.01680 

59-54 

819 

82 

I.IO2 

•0733 

1.092 

28.829 

.0706 

.001667 

.072267 

.02361 

42-35 

600 

92 

1.  122 

.0720 

I.50I 

28.420 

.0684 

O02250 

.070717 

.03289 

30.40 

444 

IO2 

I-I43 

.0707 

2.036 

27.885 

.0659 

.002997 

.068897 

•04547 

21.98 

334- 

112 

1.163 

.0694 

2-731 

27.190 

•0631 

.003946 

.067046 

•06253 

15-99 

253 

122 

1.184 

.0682 

3.621 

26.300 

•0599 

.005142 

.065042 

.08584 

11.65 

194 

132 

I.2O4 

.0671 

4-752 

25.169 

.0564 

.006639 

.063039 

.11771 

8-49 

151 

142 

1.224 

.0660 

6-165 

23.756 

.0524 

.008473 

.060873 

.16170 

6.18 

118 

IS2 

1-245 

.0649 

7-930 

21.991 

•0477 

.010716 

.058416 

.22465 

4-45 

93-3 

l62 

1.265 

.0638 

10.099 

19.822 

.0423 

-013415 

•055715 

•3I7I3 

3-15 

74-5 

172 

1.285 

.0628 

I2.758 

17.163 

.0360 

.016682 

.052682 

.46338 

2.16 

59-2 

182 

1.306 

-06l8 

15.960 

13.961 

.0288 

.020536 

.049336 

.71300 

1.402 

48.6 

192 

1.326 

.0609 

19.828 

10.093 

.0205 

.025142 

.045642 

1.22643 

.815 

39-8 

2O  2 

1-347 

.OOOO 

24.450 

5-471 

.0109 

•030545 

.041445 

2.80230 

•357 

32-7 

212 

1.367 

.0591 

29.921 

o.ooo 

.OOOO 

.036820 

.036820 

Infinite 

.000 

27.1 

By  courtesy  of  the  B.  F.  Sturtevant  Co.,  Boston. 


duct,  may  be  run  only  a  few  feet  above  the  roof  as  stated;  in  the  latter  case,  however, 
a  stack  must  be  of  sufficient  height  to  overcome  the  friction  in  the  smoke  flues,  etc. 
The  disadvantage  of  induced  draft  is  that  the  blower,  etc.,  is  more  expensive,  as  pro- 
vision has  to  be  made  to  deal  with  high  temperature,  since  the  blowers  are  placed 
between  the  boiler  and  the  stack. 


130 


STEAM-ELECTRIC  POWER  PLANTS. 


TABLE   VIII.  —  VELOCITY  CREATED.* 
When  Air  under  a  Given  Pressure  in  Inches  of  Water  is  Allowed  to  Escape  into  the  Atmosphere. 


Pressure 
in  Inches  of 
Water,  per 
Square  Inch. 

Velocity  of  Dry  Air  at  50°  Temperature 
Escaping  into  the  Atmosphere  through  any 
Shaped  Orifice  in  any  Pipe  or  Reservoir  in 
which  the  Given  Pressure  is  Maintained. 

Pressure 
in  Inches  of 
Water,  per 
Square  Inch. 

Velocity  of  Dry  Air  at  50°  Temperature 
Escaping  into  the  Atmosphere  through  any 
Shaped  Orifice  in  any  Pipe  or  Reservoir  in 
which  the  Given  Pressure  is  Maintained. 

In  Feet 
per  Second. 

In  Feet 
per  Minute. 

In  Feet 
per  Second. 

In  Feet 
per  Minute. 

O.I 

20.72 

1,243-3 

2.6 

105.33 

6,320.0 

O.2 

29.30 

1,758.0 

2.7 

107-33 

6,439-7 

0-3 

35-84 

2,150.4 

2.8 

109.28 

6,557-o 

0.4 

41-43 

2,485.6 

2-9 

III.  21 

6,672.3 

°-5 

46.31 

2,778.7 

3-o 

113.09 

6,785-5 

0.6 

50-73 

3,043-5 

3-i 

"4-95 

6,896.8 

0.7 

54.78 

3,287.0 

3-2 

116.77 

7,006.3 

0.8 

58.56 

3»$i3-S 

3-3 

118.57 

7,114.1 

0.9 

62.10 

3>726.i 

3-4 

120.34 

7,220.2 

I.O 

6545 

3,927-2 

3-5 

122.08 

7,324.7 

i.i 

68.64 

4,118.4 

3-6 

123.80 

7,427-7 

1.2 

71.68 

4,301.0 

3-7 

125.49 

7,529-3 

i-3 

74.60 

4,476.1 

3-8 

127.16 

7,629.4 

1.4 

77-41 

4,644-5 

3-9 

128.80 

7,728.2 

i-5 

80.  1  2 

4,806.9 

4.0 

130.43 

7,825-7 

1.6 

82.73 

4,963-9 

4-25 

134.40 

8,064.1 

i-7 

85-27 

5,116.1 

4-5 

138.26 

8,295.4 

1.8 

87.73 

5,263-7 

4-75 

142.00 

8,520.1 

1.9 

90.12 

5,407-3 

5- 

I45-65 

8,738.8 

2.0 

9245 

5>547-i 

5-25 

149.20 

8,951-8 

2.1 

94.72 

5,683.4 

5-5 

152.66 

9>I59-7 

2.2 

96.94 

5,816.5 

5-75 

156-05 

9,362.8 

2-3 

99.11 

5,946.4 

6. 

159-35 

9,561.2 

2-4 

101.23 

6,073.6 

6.25 

162.59 

9,755-4 

2-5 

103.30 

6,198.1 

6.50 

165.76 

9,945-8 

*  By  courtesy  of  the  B.  F.  Sturtevant  Co.,  Boston. 


Steam  Blower.  —  Steam  blowers  are  installed  for  each  individual  boiler  and  long 
air  ducts  are  avoided.  The  steam  assists  in  preventing  the  formation  of  clinker  and 
is  not  undesirable  in  small  amounts,  but  when  large  quantities  of  steam  are  used  in 
an  attempt  to  force  the  fire  by  thus  increasing  the  air  supply,  the  steam  will  rapidly 
deaden  the  fire.  Lack  of  knowledge  on  this  point  has  often  resulted  in  much  trouble. 
The  steam  jet  at  its  best  is,  however,  an  inefficient  method  of  moving  air,  and  a  suitable 
fan  will  be  more  economical. 


SMOKE  FLUES.  131 

I 

SMOKE  FLUES. 

Character.  —  Smoke  flues  should  be  made  as  short  and  direct  as  possible;  all  turns 
should  be  avoided,  and  wherever  these  are  found  necessary  they  should  be  of  the  largest 
radius  permissible,  as  already  pointed  out  under  chapter  on  draft.  Long  flues,  or  flues 
containing  many  crooks  or  bends,  offer  great  resistance  to  the  passage  of  the  gases  and 
cut  down  quite  appreciably  the  draft  pressure.  For  instance,  a  90°  turn  may  equal  in 
resistance  about  50  feet  of  straight  flue.  The  location  of  flue,  whether  below, 
above  or  on  the  side  of  the  boilers,  is  a  matter  of  opinion,  and  depends  largely  on  the 
type  of  boiler  selected.  European  practice  is  usually  to  place  the  flues  below  the  boilers. 
In  this  case  the  flues  are  constructed  of  masonry.  American  practice  is  generally 
to  place  the  flue  above  the  boilers;  usually  they  are  constructed  of  steel  or  iron  and 
either  carried  directly  on  the  boiler  setting  or  supported  from  the  building  structure 
above.  A  lining  is  occasionally  provided  of  brick  or  some  fireproof  material.  Some- 
times, in  addition,  flues  are  covered  with  asbestos  blocks.  The  omission  of  the 
interior  lining  will  reduce  the  first  cost  considerably,  not  only  on  account  of  the  cost 
of  the  lining  itself,  but  also  because  of  the  reduced  size  of  flue. 

Shape.  —  Owing  to  limited  space  and  other  requirements,  such  as  the  facilities  for 
connecting  to  chimney,  branch  flue  connections,  cleaning  doors,  etc.,  overhead  flues 
are  generally  made  either  square  or  rectangular  in  section.  Frequently,  however, 
they  have  circular  tops.  A  square  section,  with  circular  or  arched  top,  constitutes 
about  the  best  form  of  steel  flue,  since  the  circular  top  requires  no  stiffening  of  itself, 
and  adds  a  great  deal  of  stiffness  to  the  flue,  and  the  remaining  three  sides  offer  ample 
opportunities  for  connection  and  easy  lining.  The  square  section  here  offers  less 
resistance  to  the  passage  of  gases  than  would  the  rectangular  section  of  the  same  area, 
since  the  perimeter  is  a  factor  of  the  friction.  The  circular  or  arched  top  also  adds 
less  resistance  than  would  the  flat  top.  The  steel  flue  is  easily  supported  on  the  boiler 
setting  or  on  structural  steel. 

Size.  —  For  proportioning  the  main  flues  it  is  customary  to  allow  from  2.75  to 
3.5  square  feet  sectional  area  for  1,000  square  feet  of  boiler  heating  surface.  In  select- 
ing just  the  proper  size  of  flue  for  any  particular  case,  cognizance  must  be  taken  of  the 
type  of  boiler  to  be  used  and  the  kind  and  quality  of  coal  to  be  burned.  A  low-grade 
coal,  because  of  the  greater  excess  of  air  to  be  carried  away,  requires  larger  flues 
than  a  better  quality  of  coal.  Also  a  bituminous  or  long-flame  coal,  for  practically 
the  same  reasons,  will  require  an  addition  to  the  size  of  the  flues  over  that  required 
for  hard  or  short-flame  coals.  Extended  practice  throughout  America  and  European 
countries  has  well  established  the  above  given  limits  of  3.5  square  feet  for  very  poor  coal 
and  2.75  square  feet  for  the  better  class  of  coals.  Another  convenient  and  sufficiently 
accurate  rule  for  determining  the  size  of  the  main  smoke  flue  is  to  make  this  from 
20  to  25  per  cent  less  than  that  of  the  chimney.  Where  mechanical  draft  is  provided 
the  size  of  the  smoke  flue  may  be  30  per  cent  less  than  that  above  given. 


132 


STEAM-ELECTRIC   POWER   PLANTS. 


The  size  for  uptakes  and  branch  connections  between  the  boilers  and  main  smoke 
flue  are  generally  given  by  the  manufacturers  and  found  to  be  larger  in  proportion  than 
the  main  flue,  as  designed  according  to  the  above  rules.  It  is  not  advisable  to  reduce 
this  area,  inasmuch  as  the  additional  space  serves  to  offset  the  friction  due  to  sharp 
turns,  dampers,  etc. 

Expansion  Joints.  —  Steel  flues  are  sometimes  provided  with  expansion  joints,  and 
this  is  quite  necessary  in  flues  of  considerable  length.  In  cases  where  such  precautions 


£I\ 


FIG.  i.     Expansion  Joints. 

are  not  taken  the  constant  expansion  and  contraction,  due  to  temperature  changes, 
may  easily  cause  leakage  or  even  break  the  joints  or  destroy  the  flue.  Some  of  the 
common  forms  of  expansion  joints  are  shown  in  the  accompanying  illustration,  Fig.  i. 
A  more  expensive,  but  very  efficient  form  of  joint,  which  can  only  be  used  in  vertical 
flues,  however,  is  shown  at  right  hand  of  the  same  figure.  This  form  of  joint  has  been 


SMOKE  FLUES.  133 

made  use  of  in  the  59th  St.  power  house  of  the  New  York  Rapid  Transit  Co.  In  this 
installation  each  of  the  seventy-two  650  horse-power  B.  &  W.  boilers  is  provided  wyith 
two  lined  uptakes,  4  feet  3  inches  external  diameter,  and  provided  near  their  tops 
with  a  sand  expansion  joint  illustrated  above.  Similar  joints  are  being  installed  in 
the  smoke  flues  for  the  new  Potomac  power  plant,  Washington,  B.C. 

Leakage.  —  Flues  should  be  made  air-tight  and  all  joints  and  connections  should 
be  well  fitted,  caulked  and  riveted  to  prevent  the  leakage  of  air.  Too  much  attention 
can  hardly  be  paid  to  this  point,  since  small  leakages  distributed  over  the  area  of  a 
long  flue  will  greatly  impair  the  draft.  Such  a  case  has  recently  been  observed  by  the 
author,  where  the  leakages  in  the  steel  flues  and  radiation  reduced  the  draft  from  one 
inch  at  the  stack  bases  to  one-fourth  of  an  inch  in  the  boiler  settings. 

Doors.  — All  flues  should  be  amply  provided  with  substantial  and  accessible  clean- 
out  doors.  These  doors  should  be  tight  fitting  and  provided  with  strong  hinges  and 
fasteners.  In  cases  where  doors  and  frames  are  not  planed  to  accurate  fits,  air-tight 
joints  may  be  made  with  gaskets  of  asbestos  or  some  similar  material. 

Dampers.  —  The  branch  flues  as  well  as  main  flues  should  be  provided  with 
dampers.  These  dampers  may  either  be  of  the  sliding  or  rotating  form,  but  in  either 
case  should  be  easily  operated  and  tight  fitting.  Dampers  may  be  either  hand  operated 
or  automatically  operated  by  fluctuation  of  the  steam  pressure.  Hand-operated 
dampers  should  have  the  operating  mechanism  well  within  reach,  and  arranged  to 
clamp  the  damper  in  any  position  from  open  to  closed.  In  the  case  of  automatically 
operated  dampers,  a  series  of  boilers  may  be  controlled  from  one  automatic  damper 
regulator,  which,  in  turn,  is  controlled  by  the  pressure  of  the  main  steam  header.  In 
such  an  arrangement  the  individual  dampers  would  be  linked  together  and  worked 
by  a  common  connecting  bar.  Some  care  must  be  exercised  with  this  arrangement  to 
set  each  individual  damper  according  to  the  amount  of  draft  required  by  its  boiler,  as 
showrn  by  any  peculiarities  it  may  have  when  in  service. 

Generally  speaking,  each  branch  flue  should  be  provided  with  a  damper,  and  in 
addition  one  main  damper  should  be  provided  for  each  main  flue  near  the  point  where 
it  enters  the  chimney.  The  damper  in  the  main  flue  is  especially  necessary  where 
more  than  one  flue  enters  the  chimney,  in  order  that  repairs  may  easily  be  made  on  a 
flue  without  closing  down  the  entire  plant.  The  main  dampers  may  also  be  operated 
automatically.  Wherever  possible  the  mechanical  operation  of  dampers  should  be 
adopted,  since  in  this  manner  a  great  saving  of  coal  may  be  made  during  the  life  of 
the  plant,  without  any  very  appreciable  addition  to  first  cost.  This  saving  has  been 
shown  to  range  from  5  per  cent  to  10  per  cent,  depending,  of  course,  upon  the  man- 
ner in  which  the  firing  is  done  and  the  hand-operated  dampers  are  attended  to.  This 
saving  is  due  to  the  draft  being  accurately  regulated  to  suit  the  fire  requirements. 

Automatic  Regulator.  — There  are  a  great  many  of  these  appliances  to  be  found 
on  the  market  in  America,  as  well  as  in  European  countries,  and  for  the  most  part  they 


134 


STEAM-ELECTRIC   POWER   PLANTS. 


give  good  results  in  operation.  They  are  controlled  primarily  by  the  pressure  in  the 
main  steam  piping,  and  the  damper  operating  mechanism  so  controlled  is,  in  turn, 
operated  by  the  pressure  of  a  fluid.  The  following  illustration,  Fig.  2,  will  serve  to 


FIG.  2.     Thompson  Damper  and  Pressure  Regulator. 

show  the  general  construction  of  a  damper  regulator  which  is  sensitive  in  its  opera- 
tion. This  appliance  is  known  as  the  Thompson  automatic  damper  and  pressure 
regulator.  The  principle  upon  which  this  works  is  essentially  as  follows: 

The  pressure  is  taken  directly  from  the  boiler,  steam  pipes,  or  in  cases  where  a 
series  of  boilers  are  to  be  controlled,  from  the  main  steam  header,  and  led  directly  to 
the  under  side  of  the  piston,  shown  near  the  fulcrum  of  the  long  levers.  The  piston  rod 
is  carried  through  guides,  operated  on  the  under  side  of  the  long  lever,  which  is  balanced 
on  the  opposite  end  by  weights,  as  shown.  Variations  in  the  steam  pressure  cause  the 
piston  to  move  up  and  down,  which,  in  turn,  moves  this  corresponding  lever.  Attached 
to  this  first  lever  is  a  second  lever  which  operates  a  pilot  valve.  This  pilot  valve  con- 
trols the  flow  of  the  operating  medium  to  a  second  cylinder,  which  is  also  provided 
with  a  piston  connected  to  a  lever  near  the  bottom  of  the  apparatus.  This  latter  lever 
is  then  connected  to  the  damper  or  dampers,  ro  be  operated  through  connecting  links 
or  chains.  The  use  of  chains  here  requires  the  addition  of  counterweights  on  the 
damper  lever. 

Any  size  of  damper  up  to  6  x  12  feet,  or  even  larger,  has  been  successfully  operated 
by  a  regulator  of  this  type,  and  any  number  of  dampers  up  to  twenty  may  be  so  oper- 
ated on  one  system.  These  regulators  are  ordinarily  operated  by  water  from  the  city 
mains.  In  cases,  however,  where  a  number  of  dampers  are  to  be  operated  from  the 


SMOKE  FLUES. 


135 


same  machine,  it  has  been  found  necessary  to  use  a  water  pressure  in  excess  of  the 
ordinary  pressure  on  city  mains,  which  is  about  40  pounds.  In  the  case  of  the  Long 
Island  City  power  plant  of  the  Pennsylvania  Railroad,  for  instance,  it  has  been  found 
necessary  to  use  a  pressure  of  80  pounds  per  square  inch  in  the  operating  cylinder  of 
the  regulator.  In  this  particular  case,  however,  the  dampers  for  sixteen  525  horse- 
power boilers  are  operated  from  one  machine. 

Damper  regulators  are  generally  constructed,  and  set  to  operate  on  a  pressure 
variation  in  the  steam  pipes  of  from  i  to  2  pounds.  Very  delicate  apparatus  of  this 
kind  has  been  made  to  operate  on  a  pressure  variation  of  |  pound.  In  the  matter 
of  making  the  pressure  variation  as  small  as  possible,  it  is  very  essential  to  have  the 
dampers  move  easily  on  their  bearings.  Ball-bearing  dampers  or  dampers  suspended 
on  a  vertical  chain  are  good.  In  any  dase  a  vertical  axis  revolving  damper  offers  an 
advantage,  inasmuch  as  the  friction  is  not  so  great  in  this  type  as  with  horizontal  pivoted 
dampers. 

In  addition  to  operating  the  flue  dampers,  the  above-described  apparatus  is  fre- 
quently connected  so  as  to  control  the  mechanical  draft  to  the  boiler.  The  blower 


FIG.  3.      Boiler  Pressure  Record. 


The  Flue  Dampers  are  Equipped  with  an  Automatic 
Regulator. 


may  be  operated  in  this  case  either  by  a  steam  engine  or  an  electric  motor.     In  case 
of  the  steam-operated  fan,  a  regulating  valve  is  inserted  in  the  steam  supply,  and  the 

In  case  of  a  motor,  the  regulator  is  connected  to  a  suit- 


regulator  connected  to  this. 


136  STEAM-ELECTRIC   POWER   PLANTS. 

able  motor  controller.  The  accompanying  chart,  Fig.  3,  shows  a  record  of  the  steam 
pressure  taken  from  a  plant  where  both  dampers  and  fan  were  controlled  by  the  above- 
mentioned  appliance.  It  will  be  noticed  here  that  the  steam  pressure  during  the  day 
was  held  very  evenly  at  120  pounds,  and  during  the  night  at  90  pounds;  these  being  the 
respective  pressures  required  during  the  day  and  night. 

CHIMNEYS. 

Character.  —  In  order  that  good  combustion  may  be  obtained  it  is  necessary  that 
sufficient  draft  be  supplied,  which  may  be  done  either  by  natural  or  artificial  methods: 
the  former  being  secured  by  a  sufficient  height  of  chimney,  and  the  temperature  differ- 
ence between  gases  and  atmosphere;  the  latter  by  mechanically  forced  or  induced  draft. 
A  chimney  serves  two  purposes :  first,  to  produce  draft  in  supplying  a  certain  amount 
of  air  to  the  boiler  grate;  and  secondly,  to  carry  off  the  gaseous  products  of  combustion. 
The  first  is  accomplished  by  the  height  and  temperature  difference,  and  the  second 
by  the  internal  area  of  the  chimney,  being  based  upon  the  amount  and  character  of 
fuel  to  be  consumed,  the  arrangement  of  the  boilers  with  respect  to  the  stack,  and 
finally  the  location  and  altitude  of  the  power  plant  itself. 

Chimneys  are  supposed  to  be  air-tight  structures  with  vertical  smooth  flues,  to  carry 
off  the  gaseous  products  from  the  furnace,  which  should  be  discharged  at  such  a  height 
as  to  secure  thorough  diffusion  in  the  atmosphere.  They  should  be  also  designed  to 
maintain  a  passage  of  air  through  the  fire  sufficient  to  insure  perfect  combustion  of  the 
fuel.  Round  chimneys  are  more  efficient  in  producing  a  draft  than  those  of  square 
section.  It  is,  therefore,  natural  that  there  should  be  in  the  market  today  a  number 
of  different  makes  of  specially  designed  radial  brick  for  the  construction  of  chimneys. 
Common  bricks  for  the  construction  of  round  chimneys  are  practically  obsolete, 
owing  to  the  large  amount  of  clipping  required  and  also  the  quantity  of  mortar 
required  in  the  construction. 

Material.  —  In  modern  power  plants  these  different  types  of  chimneys  are  in  gen- 
eral use: 

First.     The  brick  chimney,  usually  of  radial  brick. 

Second.     The  steel  chimney,  frequently  lined  with  brick. 

Third.     The  concrete  chimney,  reinforced  with  iron  or  steel. 

The  radial  brick  is  in  much  more  common  use  in  the  construction  of  power  plants 
on  the  Continent,  where  it  originated,  the  steel  stack  being  much  more  common  in 
Great  Britain  and  America,  which  may  be  due  to  the  fact  that  the  plants  on  the  Con- 
tinent are  designed  for  a  longer  life  than  those  in  other  countries,  it  being  the  opinion 
of  continental  engineers  that  steel  stacks  are  appropriate  for  temporary  work  only. 
The  concrete  chimney  is  of  recent  date,  but  has  already  acquired  a  prominent  place 
in  power  plant  construction  in  American  practice.  Octagonal  chimneys  are  frequently 
employed  in  Great  Britain,  the  interior  section,  however,  being  circular.  This  prac- 
tice is  peculiar  to  Great  Britain. 


138  STEAM-ELECTRIC   POWER    PLANTS. 

The  item  of  cost  must  be  determined  after  the  consideration  of  many  points,  viz., 
the  size,  location  and  time  taken  for  the  erection.  A  steel  stack  may  be  more  expen- 
sive in  first  cost  than  a  brick  chimney,  if  it  is  to  be  erected  where  the  transportation 
charges  on  the  material  are  excessive,  even  though  the  manufacturers'  charges  are 
extremely  low.  This,  of  course,  assumes  a  locality  advantageous  for  the  delivery  of 
bricks  and  mortar. 

The  items  affecting  the  cost  of  different  chimneys  may  be  given  briefly  as  follows : 

I.  Size. 

II.  Character. 

III.  Location. 

IV.  Foundation  required. 
V.  Flue  connections. 

VI.     Economizers,  whether  or  not  to  be  placed  in  the  flues. 

Which  of  the  three  types  of  chimney  fulfills  its  duty  best,  and  which  is  the  most 
efficient,  is  a  question  with  widely  varying  answers,  which  may  be  seen  from  the  follow- 
ing opinions  of  the  advocates  of  the  different  kinds.  A  brick  chimney  is  made  up  of 
thousands  of  single  bricks  held  together  by  mortar.  As  these  are  of  different  materials 
it  is  said  that  the  influence  of  the  weather  will  sooner  or  later  produce  innumerable 
cracks  following  the  joints,  in  some  cases  invisible,  but,  nevertheless  present,  while 
these  joints  cannot  be  as  smooth  as  that  of  a  steel  or  concrete  chimney.  The  over-all 
diameter  of  a  radial  brick  chimney  is  greater  than  that  of  any  other  type. 

A  steel  chimney  made  up  of  many  plates,  fastened  together  with  numerous  rivets, 
has  a  radiation  loss  greater  than  that  of  any  other  type.  Should  this  chimney  now  be 
lined  with  brick,  the  inner  surface  would  not  be  as  smooth  as  the  steel  chimney  alone, 
but  exactly  the  same  as  a  brick  chimney.  Frequent  painting  of  the  steel  is  necessary 
in  order  to  prolong  its  life. 

A  concrete  chimney  is  made  up  of  a  light  shell,  reinforced  with  a  number  of  steel 
rods.  On  account  of  the  lightness  of  these  shells  the  common  proportion  of  stone 
cannot  be  used,  as  it  would  result  in  a  porous  chimney.  The  steel  reinforcement 
increases  the  radiation.  The  radiation  through  a  concrete  chimney  is  between  that 
obtained  with  a  non-lined  steel  chimney  and  a  brick  one;  provided,  of  course,  that 
none  of  them  leak. 

With  regard  to  the  appearance  of  the  different  types  of  chimney,  it  is  the  author's 
view  that  it  is  possible  to  obtain  a  much  more  elaborate  architectural  effect  with  a 
brick  chimney  than  with  any  other  at  the  same  cost.  However,  the  question  of  appear- 
ance is  purely  a  matter  of  taste,  whether  it  is  of  a  tall  massive  shaft  (brick)  or  a  tall 
and  thin  one  (steel  or  concrete).  A  businesslike  appearance  is  claimed  for  the  steel 
stack.  This,  however,  is  probably  not  the  chief  cause  for  its  adoption  in  America, 
the  first  cost  being  usually  of  paramount  importance. 

It  will  be  seen  that  the  different  types  of  chimney  have  advantages  as  well  as  dis- 
advantages, and  it  must  be  remembered  that  when  one  secures  an  advantage,  a  dis- 
advantage will  be  inevitable,  and  the  only  question  to  be  answered  is,  does  the  former 


CHIMNEYS.  139 

outweigh  the  latter  ?     If  a  power  plant  designer  is  to  build  a  plant  according  to  his  own 
judgment  the  following  may  be  of  assistance. 

Radial  Brick. — The  radial  brick  chimney  is  made  up  of  radially  formed  bricks  which 
are  usually  perforated  in  order  to  permit  a  more  thorough  burning  in  manufacture,  thus 
increasing  the  density  and  strength  and  at  the  same  time  reducing  the  weight.  This 
perforation  forms  a  space  in  the  walls  of  the  chimney,  preventing  a  certain  amount  of 
radiation,  and  forming  the  mortar  into  numerous  dowels,  making  a  very  firm  bond 
between  the  courses.  These  bricks  are  of  hard  burned  pure  clay,  and  generally  require 
no  lining  of  fire  brick,  although  this  is  sometimes  found  in  power  plant  practice.  The 
chimney  is  usually  wider  at  the  bottom  than  at  the  top,  and  offset  in  sections  inside,  while 
the  outside  is  a  smooth  conical  shaft.  The  purpose  of  the  enlarged  internal  diameter  at 
the  base  of  the  chimney  is,  in  part,  to  allow  for  the  increased  space  occupied  by  the 
hotter  gases,  and  to  reduce  the  friction.  These  radial  brick  chimneys  are  always 
designed  with  a  shell  7  to  8  inches  thick  at  the  top,  the  thickness  at  the  base,  of  course, 
varying  directly  with  the  height.  The  shaft  taper  is  about  3^  feet  in  100  feet  outside 
and  i  foot  per  100  feet  inside.  A  chimney  200  feet  high  and  12  feet  diameter  at  the 
top,  having  a  shell  thickness  of  7!  inches,  would  have  an  outside  diameter  at  the  base 
of  20  feet  3  inches,  and  an  internal  diameter  of  14  feet.  In  addition  to  this,  space 
must  be  allowed  in  laying  out  the  power  plant  for  the  square  or  octagonal  base  fre- 
quently found  with  this  type  of  brick  chimney,  either  in  the  building  or  in  the  yard. 
In  several  large  American  plants  brick  chimneys  have  been  erected  on  elevated  plat- 
forms supported  by  the  building  columns  and  spanning  the  central  firing  aisle ;  as  these 
columns  also  have  to  support  the  boilers  and  the  coal  bunkers,  a  very  heavy  construc- 
tion is  necessary.  Notable  instances  of  this  practice  are  the  Interborough  power  house 
in  New  York  City,  and  the  two  later  designed  generating  stations  of  the  New  York 
Central  Railroad  at  Port  Morris  and  Yonkers,  N.  Y.  An  advantage  of  this  con- 
struction is  that  valuable  floor  space  is  not  sacrificed,  and  all  the  space  on  the  boiler 
floor  is  available,  but  at  the  same  time  the  bunker  space  above  the  boilers  is  greatly 
reduced,  and  a  number  of  expensive  bunker  bulkheads  are  necessary.  Two  distribut- 
ing coal  conveyors  are  required  properly  to  fill  the  bunkers  to  their  capacity,  thus  mak- 
ing it  necessary  to  duplicate  certain  portions  of  the  equipment  in  order  to  guard  against 
possible  shut-downs. 

At  the  New  York  Interborough  Subway  power  plant  there  are  five  chimneys  of  this 
construction  at  present  erected,  and  provision  is  made  for  a  sixth  stack.  The  general 
dimensions  of  these  chimneys  are  as  follows: 

Height  above  grates  in  feet 225' — o" 

Diameter  at  top 15'— o" 

Base  of  chimney  above  grates      63' — o" 

Weight  of  stack  about  1,200  short  tons. 

Each  stack  serves  twelve  6,000  square  feet  Babcock  &  Wilcox  boilers;  economizers  are 
provided  for  and  forced  draft  is  installed. 


OF    THE 

UNIVERSITY 


140  STEAM-ELECTRIC   POWER   PLANTS. 

The  supporting  platform  is  carried  by  six  columns  and  is  composed  of  seven  single- 
webbed  girders,  eight  feet  deep,  two  longitudinal  and  five  lateral.  These  girders  are 
surmounted  by  fourteen  20- inch  I  beams  filled  with  concrete,  forming  a  solid  mat 
upon  which  the  brickwork  of  the  chimney  stands.  See  illustration  Fig.  2  from  an 
article  by  the  author.*  As  these  chimneys  have  sufficient  weight  to  resist  the  wind 
pressure  an  anchorage  is  unnecessary. 

The  octagonal  base  of  the  chimney  rests  upon  a  square  pedestal  placed  upon  the 
concrete  mat  and  is  surrounded  by  steel  curbing  for  a  height  of  three  feet.  At  the  top 
of  the  steel  work  is  a  layer  of  waterproofing,  covering  the  interior  area,  upon  which  are 
two  courses  of  brick;  over  these  are  built  diagonal  brick  walls  4  inches  thick,  12  inches 
apart  and  about  18  inches  high.  These  walls  are  perforated  at  intervals,  and  the 
whole  area  is  covered  with  perforated  hard  burned  terra  cotta  blocks  forming  a  cellular 
air  space  which  communicates  with  the  surrounding  air  and  serves  as  an  insulator  for 
the  protection  of  the  steel  work  beneath.  The  bottom  of  the  shaft  is  covered  with  a 
single  course  of  fire  brick  and  is  level  with  the  bottom  of  the  flue  openings,  between 
which  is  placed  a  baffle  wall  at  an  angle  of  45°  carried  4  feet  above  the  top  of  the 
flue  openings.  The  shaft  of  the  chimney  has  a  thickness  of  24  inches  at  the  bot- 
tom, decreasing  in  eight  regular  sections  to  8f  inches  at  the  top.  The  flue  open- 
ings are  lined  with  fire  brick,  as  is  the  lower  portion  of  the  chimney,  for  about 
40  feel .  At  the  roof  provision  is  made  by  which  the  steel  framing  does  not 
come  in  contact  with  the  chimney,  and  metallic  flaring  on  the  chimney  is  bent 
over  a  hood  with  louvers  upon  the  roof  to  exclude  rain. 

Reinforced  Concrete.  —  The  extended  use  of  concrete  in  power  plant  construction 
is  more  noticeable  every  day,  and  it  is  therefore  but  natural  that  its  employment  for 
chimney  construction  should  be  seriously  considered,  and  in  fact  a  great  number  of 
reinforced  concrete  stacks  have  been  placed  in  service.  These  chimneys  are  generally 
constructed  with  an  inner  and  an  outer  shell  and  an  annular  air  space.  In  some  types 
the  inner  shell  extends  entirely  to  the  top  of  the  shaft  and  in  others  it  extends  for  only 
a  portion  of  the  height.  The  purpose  of  the  two  shells  is  that  one  only  is  acted  upon 
by  the  gases,  and  subjected  to  heat,  the  outer  shell  being  practically  protected  by 
the  air  space,  the  latter  shell  being  only  exposed  to  atmospheric  conditions.  Each 
shell  is  thus  free  to  expand  independently  under  temperature  changes  which  affect  it 
alone.  These  chimneys  do  not  necessarily  require  to  be  lined,  as  it  is  claimed  that 
the  concrete  can  withstand  a  temperature  of  1,500°  Fahr.,  which  is  much  higher 
than  they  will  ever  be  exposed  to  in  power  plant  service.  The  shells  have  a  thickness 
of  from  4  to  9  inches,  dependent  upon  the  size  of  the  chimney,  and  are  reinforced  by 
iron  rods  placed  vertically  and  horizontally.  As  the  chimney  is  of  light  construction, 
a  thick  foundation  is  not  necessary  properly  to  spread  the  load,  but  the  area  of  the 
foundation  must  be  large  enough  to  provide  sufficient  stability  to  resist  the  overturning 
moment  due  to  wind  pressure,  a  factor  which  does  not  need  to  be  considered  in  those 
cases  where  the  weight  of  the  chimney  itself  is  sufficient  to  insure  its  stability.  There  - 

*  Zcitschrift  dcs  Vcrcines  dcutscher  Ingenieure,  March  4,  1905.     "  Dus  Krafthaus  der  New  Yorker  Untergrundbahn." 


CHIMNEYS. 


141 


Expanded  Metal. — : 

IfTwiskd  Rods. 

J2->/4'  Twisted  2^^°* 

Steel  Rods. 


PIG.  3.  Ransome  Reinforced  Concrete 
Chimney  at  the  Pacific  Railway  Go's 
Plant,  Los  Angeles,  Cal.  (Engineering 

Record}. 


Vertical  Bars 
Horizontal  Bars. 

(Kings) 

JHstance  betwee: 
.bars  according.to  si 


Steel 

Beniforcements 

Of  Concrete  Shell; 

'.iccto  Size  of 

Chlmuey 


Inner  Shell 
—  Air  Space 
4-  Outer  Shell 


FIG.   4.     Weber  Reinforced    Concrete 
Chimney  (Power). 


142  STEAM-ELECTRIC  POWER  PLANTS 

fore  the  reinforcing  rods  for  the  shaft  must  extend  down  into  and  be  firmly  anchored 
to  the  horizontal  reinforcement  in  the  foundation,  which  in  this  case  acts  in  a  similar 
manner  to  the  bedplate  used  with  steel  chimneys.  The  footing  is  heavily  reinforced 
by  a  grillage,  composed  of  steel  bars  or  old  steel  rails  usually  in  two  layers,  laid  at  right 
angles  to  each  other;  diagonal  grillages  are  sometimes  employed. 

With  concrete  chimneys  the  shaft  is  the  same  size  throughout  and  the  shaft  is  not 
tapered,  but  it  is  usual  to  make  the  base  or  pediment  of  a  slightly  larger  outside 
diameter  to  a  little  above  the  flue  openings,  in  order  to  provide  against  any  weaken- 
ing effect  caused  by  the  openings  necessary  at  the  base  of  the  stack;  above  this  offset 
the  shell  is  of  uniform  thickness  until  it  reaches  the  ornamental  top.  Two  makes  of 
reinforced  concrete  chimneys  are  shown  so  clearly  in  the  accompanying  cuts  that  an 
extended  description  is  unnecessary.  Fig.  3  shows  the  Ransom  chimney  of  the  Pacific 
Electric  Railway  Company  of  Los  Angeles,  Cal.,  in  which  twisted  steel  rods  are  used, 
and  the  foundation  grillage  is  of  old  steel  rails.  Fig.  4  illustrates  the  Weber  rein- 
forced concrete  chimney,  in  which  the  inner  shell  extends  practically  one-third  of  the 
height,  provision  being  made  for  this  to  expand  independently  of  the  outer  and  to 
prevent  soot  dropping  in  the  air  space  between  the  shells  at  this  point.  The  vertical 
reinforcement  used  in  this  chimney  consists  of  "T"  irons.  The  horizontal  rings  consist 
of  round  rods  spaced  about  18  inches  apart  in  the  inner  shell  and  about  3  feet  apart  in 
the  outer  shell. 

The  concrete  used  for  chimneys  is  usually  a  1:2:4  mixture,  and  to  insure  a  smooth 
and  impervious  surface  small  stones  must  be  used,  such  as  will  pass  a  f-inch  and  over 
a  |-inch  mesh.  A  very  wet  mixture  is  used  and  the  stones  are  worked  back  from  the 
surface.  In  some  other  types  of  concrete  chimneys  no  stones  are  used  at  all;  the  mix- 
ture consisting  of  i  part  cement  and  3  parts  sand.  The  advantage  of  these  types  of 
chimney  is  their  lightness  and  the  ease  and  rapidity  with  which  they  may  be  erected. 

Steel  Chimneys.  — There  are  two  types  of  steel  chimneys  in  use,  the  self-supporting 
and  the  guyed  stack;  the  former  is  more  commonly  used  for  the  larger  plants,  particu- 
larly in  cities,  while  the  latter  is  used  for  smaller  plants  in  towns  where  room  is  avail- 
able for  anchoring  the  guys.  Wire  strands,  cables  and  in  some  cases  iron  rods  are 
used  for  guys.  They  are  usually  secured  to  a  reinforcing  ring  at  a  height  above  the 
ground  equal  to  two-thirds  the  height  of  the  chimney  and  led  off  at  an  angle  of  45° 
from  the  vertical:  three  or  four  guys  are  usually  employed.  In  some  cases  two  or 
more  sets  of  guys  are  used  when  extremely  light  chimneys  of  considerable  height  are 
required;  this  type  of  construction  being  employed  where,  owing  to  extremely  high 
transportation  charges,  and  in  some  cases  customs  duties,  it  is  desirable  to  cut  down  the 
weight  to  the  lowest  possible  limit.  An  instance  of  this  is  the  two  chimneys  of  the  Rand 
Central  Electric  Works  near  Johannesburg,  South  Africa.  This  station  is  located  on  a 
high  hill,  and  the  stacks,  which  are  10  feet  in  diameter,  have  a  height  of  165  feet.  Each 
stack  is  provided  with  two  guy  rings,  one  about  halfway  up,  and  the  other  four- fifths 
of  the  height  from  the  base,  four  guys  being  attached  to  each  ring. 

A  peculiar  method  of  guying  a  stack  was  developed  to  overcome  unforeseen  condi- 


CHIMNEYS. 


143 


tions  at  the  plant  of  the  Mexican  Electrical  Works,  Ltd.,  in  the  City  of  Mexico.  This 
plant  was  designed  and  the  equipment  shipped  from  Germany.  The  stack  was  9  feet 
3  inches  in  diameter  and  165  feet  high,  with  a  small  bell-shaped  base  and  was  supplied 
with  four  guys.  Upon  its  arrival  it  was  found  that  only  two  of  the  guys  could 


FIG.  5.     Self-Supporting  Steel  Chimney  (Power). 

be  anchored,  as  a  street  had  been  opened  cutting  off  the  other  anchorages,  and  the 
following  method  was  adopted  for  securing  the  stack.  The  guys  were  wrapped  heli- 
cally around  the  chimney  and  secured  by  turn-buckles  to  the  foundation.  This  chimney, 
erected  in  1897,  is  still  in  service  in  a  country  subject  to  earthquakes. 


144 


STEAM-ELECTRIC   POWER   PLANTS. 


Owing  to  transportation  difficulties  it  is  not  always  advisable  to  use  steel  stacks  for 
such  plants,  and  at  an  electric  plant  at  Para,  Brazil,  a  brick  stack  was  found  less 
expensive,  although  the  entire  building  was  of  steel  frame  construction  with  corru- 
gated iron  roof  and  sides. 

Guyed  Chimneys.  —  Guyed  chimneys  are  usually  straight  cylinders,  while  self- 
supporting  stacks  have  a  conical  base  or  bell.  These  chimneys  are  built  in  sections 
of  convenient  length,  the  thickness  of  the  plate  being  usually  J  inch  at  the  top  and 
increasing  toward  the  base,  usually  each  ring  laps  over  the  ring  below.  In  this  con- 
struction each  ring  is  a  section  of  a  cone,  although  the  taper  is  so  slight  as  to  be  imper- 
ceptible, and  the  shaft  is  practically  a  cylinder.  In  some  cases  this  practice  is  not  fol- 


FIG.  6.     Steel  Chimneys  in  Process  of  Erection,  Long  Island  City  Plant. 

lowed,  the  rings  being  made  straight  with  alternate  inside  and  outside  laps,  in  other 
instances  the  sections  are  assembled  with  the  horizontal  laps  made  by  the  lower  ring 
coming  outside  of  the  upper,  straight  rings  being  used  and  a  gradual  taper  is  obtained 
for  the  shaft  in  this  way.  A  trolley  ring  is  frequently  provided  close  to  the  top  of  the 
stack  with  a  trolley  and  a  block,  by  which  a  man  can  be  hoisted  when  it  is  necessary 
to  paint  the  stack.  Ornamental  galleries  and  railings  are  occasionally  placed  just 
below  the  top  of  the  chimney. 


CHIMNEYS.  145 

Self-Supporting.  —  The  base  of  self-supporting  chimneys  is  bell-shaped,  being 
flared  out  for  a  height  of  ^  to  £  the  height  of  the  chimney,  the  diameter  at  the  base 
is  from  £  to  TV  of  the  height,  but  is  often  fixed  by  other  considerations.  The  bell  is 
occasionally  proportioned  on  the  diameter  of  the  stack,  the  height  being  from  i^  to 
2\  times  the  diameter,  and  the  diameter  of  the  base  plate  being  from  one  and  a  half  to 
twice  the  stack  diameter.  It  will  be  noted  that  these  two  methods  are  substantially 
in  agreement.  A  heavy  circular  cast-iron  bedplate  is  used  below  the  bell,  the  founda- 
tion bolts  passing  up  through  the  bedplate,  and  steel  brackets  riveted  to  the  shell. 
In  some  cases,  however,  the  bedplate  is  secured  to  the  foundation  and  the  shell  is 
riveted  to  it.  The  foundation  contains  a  number  of  heavy  anchor  plates  for  the  hold- 
ing down  bolts,  or  in  some  cases  a  grillage.  This  foundation  must  extend  to  a  suffi- 
cient height  above  the  ground  to  protect  the  stack  and  bedplates  from  ground 
moisture,  and  must  be  of  sufficient  area  and  weight  to  resist  the  wind-overturning 
moment. 

Lining.  —  It  is  often  claimed  that  where  there  is  a  long  smoke  flue  between  the 
boiler  and  the  stack,  it  is  unnecessary  to  line  steel  chimneys ;  this  would  be  true  if  the 
deteriorating  effect  of  the  hot  gases  alone  was  to  be  reckoned  with,  but  the  province  of 
the  chimney  is  to  provide  a  draft,  and  it  can  only  do  this  when  there  is  a  sufficient  differ- 
ence in  temperature  between  the  internal  column  and  the  external  air  to  provide  head 
enough  for  this  purpose.  A  large  quantity  of  heat  will  be  lost  by  an  unlined  stack, 
and  such  losses  are  much  more  serious  when  low  stack  temperatures  are  dealt  with 
than  when  hot  gases  are  handled.  The  duty  of  the  lining  is  not  only  to  prevent  corro- 
sion, but  to  act  as  a  heat  insulator.  t 

There  is  a  considerable  variation  in  practice  in  regard  to  lining  steel  chimneys;  in 
some  cases  only  the  lower  portion,  in  others  one-half  the  height  is  lined,  and  fully  lined 
stacks  are  often  used.  The  lower  portion  of  the  lining  is  fire  brick,  and  this  is  some- 
times continued  for  the  full  height ;  in  other  cases  the  upper  portion  of  the  stack  is  lined 
with  hard  red  brick,  the  upper  lining  rarely  exceeds  4^  inches  in  thickness,  and  the 
thickness  increases  in  regular  steps  to  the  base,  the  length  of  each  section  varying  from 
20  to  50  feet,  according  to  circumstances.  The  regular  practice  is  to  allow  an  air  space 
between  the  lining  and  the  shell,  though  in  some  cases  this  space  is  filled  with  sand;  in 
the  stack  of  the  Pennsylvania,  New  York  &  Long  Island  Railroad  power  plant  a  concrete 
backing  is  used.  In  some  full  and  half  lined  stacks  the  lining  is  divided  into  a  number 
of  sections  vertically,  each  ring  having  a  depth  of  from  10  to  25  feet,  and  being  sup- 
ported by  "Z"  bars  or  angles  riveted  to  the  shell  with  an  allowance  for  vertical  expan- 
sion between  the  rings;  such  linings  are  usually  the  same  thickness  throughout  their 
height.  But  in  all  cases  the  base  of  the  stack  is  supplied  with  a  heavier  lining,  owing 
to  the  hottest  gases  being  at  this  point. 

It  is  necessary  that  a  chimney  lining  should  be  free  to  expand,  particularly  where  it 
is  exposed  to  hot  gases,  that  is,  provision  of  this  character  is  more  necessary  at  the  base 
than  at  the  top.  All  brickwork  expands  and  contracts  more  or  less  under  temperature 
variations,  and  where  the  attempt  is  made  to  rigidly  confine  this  structure,  it  will  work 


146  STEAM-ELECTRIC  POWER  PLANTS. 

itself  to  pieces  and  fall  down  in  patches,  resulting  in  serious  local  corrosion  and  weaken- 
ing of  the  steel  work. 

One  of  the  latest  steel  stacks  built  is  that  of  the  Long  Island  City  power  plant  of 
the  Pennsylvania,  New  York  &  Long  Island  Railroad.  This  stack  has  an  internal 
diameter  of  16  feet  and  is  275  feet  high  above  the  base. 

These  chimneys  serve  a  double  decked  .boiler  house  and  are  provided  with  six  smoke 
flue  openings  and  one  opening  for  a  cleaning  door,  and  are  unique  in  arrangement. 
The  four  upper  flue  openings  are  connected  with  economizers  through  which  the  waste 
gases  pass.  The  two  lower  flue  openings  are  in  the  boiler-room  basement  and  connect 
with  the  by-pass  flue  of  the  economizers.  The  lower  portion  of  the  stack  is  separated 
into  halves  by  a  baffle  wall.  Immediately  above  the  lowest  flue  opening  a  floor  with  a 
horizontal  damper  is  placed  in  each  half  of  the  shaft,  and  the  division  wall  below  this 
floor  is  pierced  by  an  opening  supplied  with  dampers,  the  purpose  of  this  arrangement 
being  to  by-pass  any  one  of  the  chimneys  should  it  be  desired  to  do  so.  The  bottom  of 
the  chimney  is  flared  out  to  a  diameter  of  23  feet,  and  above  the  bell  cylindrical  rings 
are  used,  the  upper  plates  in  all  cases  telescoping  inside  the  lower,  so  that  a  slight  taper 
runs  through  the  shaft.  The  upper  edges  of  the  rings  are  planed  to  a  level,  and  during 
erection  these  joints  were  calked  tight  to  prevent  rain  working  in.  A  single  brick 
lining  is  used  throughout,  and  supported  at  20  feet  intervals  by  horizontal  "Z"  bar 
rings.  The  space  between  the  lining  and  the  shell  was  grouted  full  of  cement  mortar 
to  protect  the  steel;  in  the  bell  the  lining  is  backed  by  red  brick  for  a  height  of  64  feet. 
The  stack  is  riveted  to  a  segmental  cast-iron  bedplate,  held  down  by  20  3-inch  anchor 
bolts  which  pass  through,  and  are  held  by,  a  grillage  of  steel  rails  in  the  bottom  of  the 
foundation.  The  top  of  the  chimney  is  finished  by  a  segmental  cast-iron  astragal  and 
a  "Z"  bar  painting  ring.  Just  above  the  boiler-house  roof  is  a  rain  shield  or  flashing 
riveted  to  the  stack.  The  rings  were  assembled  at  the  shop  before  shipment  and  the 
rivet  holes  reamed.  The  complete  equipment  of  four  stacks  was  erected  in  about 
three  and  one-half  months.  This  power  plant  rests  on  wood  piling  spaced  2  feet 
4  inches  centers,  above  which  is  a  mattress  of  concrete  6  feet  6  inches  thick  over  the 
entire  building,  increased  at  the  stacks  to  a  thickness  of  8  feet  6  inches. 

Baffle  Wall.  —  Chimneys  having  two  or  more  flue  openings  should  be  provided 
with  baffle  or  division  walls  placed  at  an  angle  with  the  axis  of  the  flues,  usually  at 
45°,  by  which  the  two  opposing  currents  of  hot  gases  are  turned  up  the  stack  with  but 
slight  loss  of  velocity,  in  a  sort  of  a  whirl,  the  office  of  the  wall  being  principally  to  pre- 
vent the  two  currents  of  gas  from  impinging  on  each  other,  and  thus  reducing  the 
efficiency  of  the  chimney.  These  walls  extend  a  few  feet  above  the  flue  openings  and 
in  a  two  or  three  story  boiler  house  the  baffle  wall  should  be  continued  up  above  the 
highest  opening,  though  this  is  sometimes  considered  unnecessary,  as  was  the  case  in 
the  Pennsylvania,  New  York  &  Long  Island  chimney,  described  above. 

Ladders.  —  Chimneys,  no  matter  how  constructed,  should  be  provided  with  per- 
manent means  for  climbing  them.  For  a  steel  chimney  a  ladder  is  provided  on  the 
outside,  and  a  boatswain  chair  must  be  used  for  painting  or  inspecting  the  lining. 


CHIMNEYS.  147 

Brick  chimneys  usually  have  a  ladder  inside,  formed  of  suitable  iron  steps  anchored 
in  the  brickwork,  and  in  many  cases  an  outside  ladder  of  similar  construction  is  provided; 
ladders  of  this  kind  can  be  used  on  concrete  chimneys. 

Lightning  Arresters.  —  Protection  from  lightning  comes  within  the  same  category 
as  fire  insurance,  that  is,  it  is  simply  good  business  policy.  Lightning  may  never  come 
near  a  chimney,  but  there  is  no  reason  for  omitting  the  rod,  any  more  than  there  is  for 
omitting  the  fire  insurance  on  goods  stored  in  a  fireproof  building.  A  great  many  chim- 
neys have  been  struck  by  lightning  and  badly  damaged,  if  not  completely  destroyed. 
The  damage  in  such  cases  is  not  confined  to  that  done  to  the  chimney  itself,  but  adja- 
cent property  is  damaged  by  falling  debris,  and  in  most  cases  the  complete  shut-down 
of  the  plant  results.  A  steel  chimney  is,  of  itself,  an  excellent  lightning  conductor  and 
protects  all  surrounding  property.  Brick  and  concrete  chimneys  are  non-conductors, 
but  the  ascending  current  of  hot  gases  presents  a  path  tending  to  attract  the  discharge 
of  atmospheric  electricity.  A  number  of  methods  are  used  for  protecting  them,  rang- 
ing from  a  single  point  extending  high  enough  above  the  chimney,  in  some  cases  10  to 
13  feet,  to  a  number  of  points  one  foot  high  at  intervals  of  two  feet  around  the  circum- 
ference of  the  top.  When  a  single  point  is  used  it  is  sometimes  counterweighted  to 
keep  it  upright  and  arranged  to  be  lowered,  the  supporting  cable  serving  as  the  light- 
ning conductpr;  or  two  cables  may  be  used,  one  acting  as  a  guy  to  keep  the  point  ver- 
tical, the  other  serving  to  lower  it.  In  some  cases  the  chimney  has  a  metal  crown  of 
decorative  design  which  serves  the  purpose  of  the  point  on  a  lightning  rod  and  is  con- 
nected to  earth  in  a  similar  manner. 

Lightning  rod  points  should  be  blunt  cones,  with  a  base  radius  equal  to  their  height, 
and  may  be  made  from  gilded  copper,  platinum,  nickel  plated  copper,  or  iron  gilded  or 
nickel  plated  to  resist  oxidization.  The  conductor,  if  of  copper,  should  weigh  about 
6  ounces  per  foot,  and  when  in  cable  form  no  individual  wire  should  be  less  than  No.  12 
B.W.G.;  an  iron  rod  should  weigh  2\  pounds  per  foot,  and  should  be  galvanized  or 
tinned.  All  joints  in  the  conductor  should  be  soldered,  for,  although  lightning  can 
jump  bad  joints,  it  is  better  not  to  rely  on  such  properties  of  discharge.  The  con- 
ductor should  be  free  from  abrupt  bends  and  should  be  supported  by  insulated  hangers 
of  the  same  materials.  It  is  led  down  the  outside  of  the  chimney,  preferably  near  a 
ladder,  for  ease  of  inspection,  as  well  as  installation.  When  stacks  are  erected  in  steel 
frame  buildings  the  lightning  rod  is  sometimes  grounded  on  the  frame;  this  is  not 
desirable  unless  the  frame  is  also  well  grounded  to  the  earth. 

The  ground  connection  should  be  made  where  the  earth  is  permanently  damp,  or 
the  conductor  may  terminate  below  the  water  in  a  well  or  other  body  of  water.  Copper 
ground  plates  are  from  &  to  J  inch  thick  and  iron  plates  \  inch  thick,  galvanized, 
and  are  preferably  surrounded  by  crushed  coke.  They  should  have  a  total  surface  of 
from  1 8  to  20  square  feet,  or  copper  strips  having  an  equal  area  may  be  laid  in  a  trench 
surrounded  by  coke.  The  ground  plate  should  be  buried  below  the  ground  water  line  or 
near  the  discharge  of  rain-water  leaders  or  other  pipes  tending  to  keep  the  earth  moist 
when  possible.  In  many  cases  two  independent  ground  connections  are  insisted  upon. 


148  STEAM-ELECTRIC   POWER   PLANTS. 

BOILER   FEED   WATER. 

Pure  Water.  —  Water  in  its  natural  state  is  never  found  absolutely  pure,  and  abso- 
lutely pure  water  is  impossible  to  obtain  except  by  distillation.  Requirements  for 
different  industries,  in  regard  to  water,  vary  so  greatly  that  it  would  be  impossible  to 
establish  a  standard  which  would  be  valid  in  all  cases;  in  industrial  practice  the  highest 
degree  of  purity  is  not  required,  even  if  the  cost  of  supplying  pure  water  did  not  forbid. 
What  is  needed  is  not  an  absolutely  pure  water,  but  a  suitable  water.  Not  every  water 
is  suitable  for  boiler  feeding.  The  question  to  be  considered  is,  how  to  secure  the  best 
possible  water  available  in  the  district  where  the  boilers  are  used.  Provided  that  no 
suitable  water  is  obtainable,  means  can  be  adopted  to  purify  it  to  a  degree  that  will 
make  its  use  economical. 

Impure  Water.  — The  feed  water  for  the  boilers  must  not  injure  the  metal  of  which 
the  boilers  are  built,  it  must  be  as  free  as  possible  from  air,  carbonic  acid,  salts  of 
ammonia,  decomposed  foods,  chlorides,  etc.,  and  it  must  not  produce  scale  by  the 
deposit  of  sulphates  of  lime,  carbonate  of  lime,  magnesia,  alumina  and  iron,  which 
not  only  reduce  the  efficiency  of  the  boilers,  but  likewise,  if  neglected,  render  them 
dangerous.  In  addition  to  this,  impurities  cause  considerable  expense  in  the  way  of 
delay,  cleaning  and  repairs,  and  the  loss  due  to  the  necessity  of  blowing  down  at  more 
frequent  intervals  than  would  be  necessary  had  better  water  been  supplied.  In  fact 
this  blowing  down  of  the  boilers  is  one  of  the  serious  heat  losses  of  the  plant,  while  the 
amount  of  energy  wasted  in  this  matter  is  too  frequently  not  recognized  by  power  plant 
designers. 

The  amount  of  solids  deposited  in  a  boiler  is  often  astonishing;  over  300  pounds  per 
month  may  be  deposited  in  a  100  horse-power  boiler,  using  water  which  shows  only 
7  grains  of  solids  per  U.S.  gallon,  and  in  some  localities  a  boiler  can  only  be  operated 
two  or  three  days  between  cleanings.  The  impurities  met  with  in  feed  water  may 
produce  one  or  several  of  the  following  results: 

I.  Internal  corrosion  of  the  boiler. 

II.  Precipitation  of  mud,  etc. 

III.  Formation  of  scale. 

IV.  Scum,  which  causes  excessive  priming  or  foaming. 

Boiler  Corrosion.  —  Pitting  and  corrosion  are  caused  by  free  acids  which  are 
either  in  the  original  water  or  are  liberated  by  the  splitting  up  of  some  salt  in  the  water. 
These  acids  may  be  of  vegetable  origin,  derived  from  some  adulterant  of  the  lubricat- 
ing oil  used,  or  the  original  water  may  have  been  polluted  with  ashes  from  some  neigh- 
boring industrial  works  or  mine,  or  the  water  may  have  been  taken  from  swamps  or 
bogs  which  often  contain  humic  or  vegetable  acids.  Sulphuric  acid  is  found  in  mine 
drainage,  and  is  also  absorbed  from  the  atmosphere. 

Air  absorbed  by  water  is  freed  by  boiling  and  produces  some  corrosion.  The 
peculiar  activity  of  oxygen  under  such  circumstances  is  perhaps  due  to  the  fact  that 


BOILER  FEED  WATER.  149 

whereas  ordinary  air  is  a  mixture  of  oxygen  and  nitrogen  in  the  approximate  ratio  of 
i  to  4,  when  the  air  is  dissolved  in  water  it  becomes  a  mixture  of  i  part  oxygen  and 
only  1.87  parts  of  nitrogen,  owing  to  the  greater  solubility  of  oxygen.  The  result  is 
that  when  this  air  is  liberated  there  is  a  large  amount  of  free  oxygen  which  unites  with 
the  iron,  usually  forming  pits  of  small  area  but  of  considerable  depth.  The  activity 
of  the  oxygen  is  not  rapid  at  high  temperatures,  but  it  attacks  the  iron  most  rapidly 
when  the  boiler  is  only  in  use  a  portion  of  the  time,  therefore  there  is  more  rapid  corro- 
sion in  boilers  where  there  are  many  shut-downs,  and  also  in  the  feed- water  pipes  where 
the  temperature  falls  within  the  range  at  which  the  oxygen  is  most  active. 

When  alkaline  water  is  used,  it  is  very  liable  to  attack  copper  fittings,  par- 
ticularly should  the  circulation  be  defective.  The  oxygen  attacks  the  copper  and  the 
alkali  dissolves  the  copper  oxide  so  formed,  whereby  a  fresh  surface  of  copper  is  pre- 
sented to  the  attacks  of  the  oxygen.  With  such  waters  heavy  boiler  plates  have  been 
pitted  through  in  a  few  months. 

Mud.  — When  provision  is  made  to  catch  the  mud  and  blow  it  off  before  it  settles 
on  the  heating  surface  the  only  evil  effect  is  the  cost  of  the  heat  lost.  If  this  mud, 
however,  is  carried  along  and  deposited  on  the  heating  surface,  it  may  unite  with  the 
scale-forming  materials  present  in  the  water,  and  the  mass  will  be  baked  on  the  surface 
of  the  plates  and  tubes,  forming  a  very  hard  scale  which  is  costly  and  difficult  to  remove. 

Boiler  Scale.  —  The  effect  of  scale  depends  largely  upon  its  density.  Those 
formed  by  carbonates  are  usually  soft  and  porous,  and  their  retarding  effect  upon  heat 
transmission  is  small,  except  when  present  in  large  quantities.  Sulphates  and  a  few 
other  impurities  deposit  a  hard  scale,  so  hard  that  they  can  only  be  removed  by 
chipping  or  cutting  them  loose  by  some  sort  of  a  machine.  These  scales  are  impervious 
to  water,  and  are  a  source  of  positive  danger,  because  the  metal  upon  which  they  have 
been  deposited  cannot  transmit  its  heat  to  the  water  in  the  boiler,  which  is  liable  to 
burn,  crack  or  should  the  metal  reach  a  red  heat,  bulges  will  be  formed,  or  possibly 
a  partial  destruction  of  the  boiler  will  occur. 

The  following  are  the  most  common  scale- forming  materials: 

Calcium  (lime)  Carbonate,  CaCO3.          Calcium  Sulphate,  CaSO4. 

Magnesium  Carbonate,         MgCO3.          Magnesium  Sulphate,  MgSO4. 

The  following  materials  are  found  usually  in  small  quantities,  and  far  less  frequently 
than  those  first  mentioned: 

Iron  Carbonate,  Fe2CO3.  Iron  Oxide,  Fe2O3. 

Magnesium  Chloride,  MgCl2.  Iron  Hydroxide,  Fe2(OH)6. 

Calcium   (lime)    Chloride  CaCl2.  Calcium  Phosphate,  Ca3(PO4)2. 

Potassium  Chloride,  KC1.  Silica,  Si. 

Sodium  Chloride.  NaCl. 

and  organic  matter  of  various  kinds. 


150  STEAM-ELECTRIC   POWER   PLANTS. 

Magnesium  and  calcium  carbonate  are  but  slightly  soluble  in  water  and  are  usually 
combined  with  carbon  dioxide,  forming  bicarbonates  of  calcium  and  magnesia  (CaH2 
(CO3)2  and  MgH2  (CO3)2),  which  are  quite  soluble  in  cold  water.  When  this 
water  is  heated,  the  carbon  dioxide  (CO2)  is  driven  off,  decomposing  the  bicarbonates 
and  precipitating  the  comparatively  insoluble  mono-carbonate  of  lime  and  magnesium 
hydrate.  This  decomposition  occurs  between  the  temperatures  of  180°  to  290°  Fahr. 
The  scale  formed  by  carbonate  of  calcium  is  comparatively  porous  and  does  not  adhere 
strongly  to  metal,  and  is,  therefore,  not  troublesome,  unless  present  in  large  quantities. 
This  is  also  true  of  magnesium  carbonate  alone,  but  this  substance  follows  the  water 
currents  and  settles  very  slowly,  and  when  other  substances  are  present  it  tends  to 
cement  them  together,  forming  a  more  troublesome  scale.  These  substances  will  often 
cause  violent  thumping  in  the  boiler,  which  may  have  serious  results.  The  magnesium 
and  calcium  sulphates  are  the  most  troublesome  scale-forming  impurities.  They 
are  not  deposited  until  about  the  temperature  of  300°  Fahr.  is  reached.  The  mag- 
nesium sulphate  deposits  a  mono-hydrated  salt,  and  its  presence  is  objectionable 
because  it  interferes  with  the  removal  of  other  impurities.  Calcium  sulphate  is  de- 
posited in  long  needle-like  crystals,  which  have  active  cementing  properties,  and  when 
mingling  with  other  matters  form  a  very  hard  and  troublesome  scale. 

The  iron  carbonate  behaves  in  a  similar  manner  to  the  calcium  mono-carbonate, 
but  it  only  occasionally  occurs,  and  usually  in  such  small  quantities  that  its  effects 
are  negligible. 

Magnesium  chloride  is  deposited  as  a  hydroxide,  and  as  it  has  very  active  cementing 
properties  it  is  decidedly  objectionable. 

The  others,  potassium  chloride,  calcium  and  sodium  chlorides  (common  salt),  give 
little  trouble  from  incrustation,  unless  allowed  to  concentrate  beyond  the  saturation 
point,  when  they  are  deposited  and  increase  the  bulk  of  the  scale.  They,  however, 
possess  no  cementing  properties  in  themselves,  but  may  cause  foaming,  which  will  be 
greater  as  the  specific  gravity  of  the  solution  increases.  The  only  remedy  for  these 
impurities  is  frequent  blowing  down,  which  prevents  their  concentration. 

Scum.  —  Sewage  and  vegetable  matter,  when  present  in  the  boiler,  form  a  glutinous 
skin  on  the  surface  of  the  water,  which  may  be  so  serious  as  to  interfere  with  the  working 
of  the  plant.  Some  of  these  materials  may  be  due  to  animal  or  vegetable  compounds 
used  as  dilutents  to  the  cylinder  oil,  which  enter  the  boiler  from  the  hot  well  and  con- 
denser. When  soda  compounds  are  used  in  the  boiler,  or  contained  in  the  feed  water, 
these  oils  may  be  saponified,  in  such  a  case  "soapsuds"  and  violent  thumping  are 
the  result.  A  surface  blow-off  is  a  good  method  of  handling  scum,  but  such  blow-offs 
are  troublesome  in  operation. 

Dervaux-Reisert  Purifier. — The  importance  of  the  installation  of  water-purifying 
apparatus,  where  impure  boiler  feed  water  is  to  be  used,  is  frequently  grossly  neglected 
by  the  power  plant  designer.  The  first  cost  of  the  water-purifying  system  is  not  of 
great  importance,  and  the  larger  the  plant  the  cheaper,  comparatively.  The  cost 


BOILER  FEED  WATER.  151 

of  maintenance  is  also  low,  as  the  price  of  the  chemicals  used  is  small,  and  it  does 
not  require  close  attention.  This  is  in  many  cases  due  to  the  fact  that  their  designers 
do  not  appreciate  the  benefit  derived.  It  is  the  author's  purpose  to  describe  here  an 
apparatus,  several  of  which  have  been  installed  under  his  supervision,  and  excellent 
results  obtained  from  the  same. 

The  accompanying  illustration,  Fig.  i,  represents  an  automatic  water-purifying 
apparatus,  as  most  generally  used  in  Europe,  and  also  in  America.  This  apparatus 
consists  of 

I.  A  continuously  acting  Dervaux  lime  saturator; 

II.  Distributing  apparatus; 

III.  Reaction  chamber; 

IV.  Reisert  gravel  filter; 

and  is  marketed  in  New  York  and  London  by  the  Hans  Reisert  Co.,  Ltd.,  of  Cologne, 
Germany.  The  principle  on  which  the  apparatus  is  constructed  is  as  follows : 

Hydrate  of  lime  (caustic  lime)  is  the  cheapest  precipitant  of  all  bicarbonates,  and 
when  calcined  soda  (carbonate  of  soda)  is  used  at  the  same  time  it  precipitates  sul- 
phates and  other  compounds  much  more  cheaply  than  caustic  soda,  which  is  used  in 
many  other  purifying  processes.  As  lime  cannot  be  dissolved  like  soda  to  any  desired 
degree  of  concentration  in  water,  and  as  milk  of  lime  cannot  be  used  continuously  in 
equal  quantities,  the  advantage  is  taken  of  the  property  of  lime  by  which  it  becomes 
dissolved  in  the  fixed  ratio  of  i :  778  in  the  water  and  thus  saturates  the  latter.  Beyond 
this  point  water  takes  up  no  more  lime  in  solution.  The  Dervaux  lime  saturator  con- 
sists essentially  of  an  upright  conical  vessel  S,  the  smallest  section  of  which  is  at  the 
bottom.  The  previously  prepared  milk  of  lime  (made  by  slaking  and  diluting  the 
lime  in  the  vessel  J)  is  introduced  through  the  stopcock  K  and  the  tube  k  into  the 
bottom  of  the  lime  saturator  after  the  exhaust  lime  residue  has  been  drawn  off  imme- 
diately before  through  the  cock  L.  An  accurately  regulated  constant  water  supply 
flows  from  the  regulating  vessel  R  through  the  cock  V  and  the  tube  v  into  the  mass  of 
lime,  which  has  been  introduced  and  gives  it  a  continuous  whirling  motion.  The 
water  carries  the  lime  upwards  until  the  velocity  of  the  water  becomes  so  small,  in  con- 
sequence of  the  increasing  cross-section,  that  the  heavier  particles  of  lime  cannot  follow. 
As  a  consequence  the  lime  water,  which  has  thus  become  completely  saturated  with 
lime,  leaves  the  lime  saturator  in  a  clear  state  through  the  tube  U.  The  particles  of 
lime  which  fall  back  are,  therefore,  continually  seized  by  the  current  of  the  water  and 
whirled  about  until  they  are  completely  absorbed. 

The  lime  water  flows  from  the  lime  saturator  into  the  mixing  pipe  E  in  the  reaction 
chamber.  Into  this  tube  flow  also  the  soda  solution  from  the  chamber  C  of  the  dis- 
tributing apparatus  by  means  of  a  siphon  N  and  the  crude  water  through  the  cock  P 
from  the  chamber  R.  In  this  reaction  chamber  a  part  of  the  precipitated  sediment 
is  deposited,  from  whence  it  may  be  removed  through  the  mud  gate  W  from  time  to 
time.  The  water  in  chamber  D  rises  slowly  upwards  and  enters  the  top  of  the  tube 
by  which  it  is  conducted  to  the  Reisert  filter  F  and  then  leaves  the  purifying  apparatus 


152 


STEAM-ELECTRIC   POWER   PLANTS. 


FIG.  i.     Dervaux-Reisert  Automatic  Water  Purifying  Apparatus. 


BOILER   FEED   WATER.  153 

perfectly  clear  through  the  tube  Z  and  the  three-way  cock  M  and  is  carried  off  by  the 
waste  pipe  T.  The  material  of  the  filter  never  needs  renewing.  It  takes  about  five 
minutes  to  cleanse  it,  and  this  has  to  be  done  about  once  or  twice  a  day  or  even  less 
frequently,  according  to  the  quantity  of  mud.  It  is  washed  as  follows : 

Open  the  mud  gate  O  and  adjust  the  two  three-way  cocks  in  such  a  manner  that 
the  water  flowing  into  the  apparatus  enters  it  through  the  pipe  Z  beneath  the  filter 


FIG.  2.       Automatic  Water  Purifying  Plant  (Dervaux-Reisert)   of  12,000  gal.    per    hour 
capacity  at  the  Power  Plant  of  the  Syracuse  Lighting  Co.,  Syracuse,  N.  Y. 

material  instead  of  entering  the  distributing  chamber.  Then  turn  on  the  air  com- 
pressor. While  the  compressed  air,  which  is  led  beneath  the  filtering  material,  stirs 
it  up  violently  and  loosens  the  mud  particles,  the  water  that  flows  back  carries  them 
along  and  takes  them  to  the  mud  gate.  The  air  compressor  must  be  closed  again 
after  two  or  three  minutes,  but  the  water  still  allowed  to  flow  until  the  water  leaving  by 
the  mud  gate  O  is  quite  clear.  Then  the  three-way  cocks  M  are  put  back  again  in 


154  STEAM-ELECTRIC   POWER   PLANTS. 

their  original  positions.  The  apparatus  has  been  found  especially  useful  in  purifying 
waters  which  often  change  their  composition  and  waters  which  contain  much  mud  as 
river  waters,  for  instance.  The  apparatus  has  also  been  used  with  the  best  results  for 
the  removal  of  oil  from  the  water  of  condensers. 

The  accompanying  illustration,  Fig.  2,  shows  the  purifying  apparatus  at  the 
power  plant  of  the  Syracuse  Lighting  Company,  Syracuse,  N.  Y.  The  water  to 
be  treated  is  taken  from  the  Oswego  Canal,  which  varies  frequently  in  its  character 
and  at  times  shows  a  hardness  of  25°,  American.  This  purifying  plant  is  of  the  above- 
described  Reisert  system  and  consists  of  two  apparatus,  one  of  which  is  shown  in  the 
illustration,  each  having  an  hourly  capacity  of  12,000  gallons.  The  power  plant  con- 
sists partly  of  turbines  and  partly  of  reciprocating  engines;  the  water  of  condensation 
from  the  turbines  is  mixed  with  the  make-up  water,  thereby  raising  the  temperature  of 
the  water  delivered  to  the  filters,  a  smaller  apparatus  than  otherwise  necessary  is  there- 
fore required. 

An  apparatus  of  still  greater  importance  in  modern  power  plant  designing  has 
recently  been  introduced  in  the  market  after  being  thoroughly  tried  in  Germany  by 
the  same  company.  It  is  a  modification  of  the  above-described  type.  It  needs  even 
less  attention  and  has  the  great  advantage  that  it  can  purify  water  at  any  tempera- 
ture. The  chemicals  to  the  former  are  supplied  proportionately  in  an  automatic 
manner,-  while  for  the  latter  system  they  may  be  supplied  in  a  larger  quantity  for  an 
extended  period.  The  principal  chemical  used  is  barium  carbonate.  Apparatus 
of  this  kind  have  been  installed  at  Frankfort-on-the-Main  and  elsewhere,  and  after 
being  thoroughly  tested  were  found  to  give  satisfaction  in  every  respect. 

Storage.  —  Where  boiler  feed  water  is  drawn  directly  from  the  city  mains,  surge 
tanks  should  be  installed  in  order  to  procure  for  the  pumps  a  steady  water  supply. 
These  tanks,  in  smaller  plants,  are  frequently  located  on  the  roof  of  boiler  house ;  where, 
however,  the  tanks  are  too  large  for  this  they  may  be  installed  in  the  basement  of  the 
boiler  room  or  outside  of  the  building,  in  the  latter  case  they  may  be  located  on  an 
elevated  structure.  If  these  tanks  are  fed  directly  from  the  city  mains,  the  discharge 
pipe  into  tanks  should  be  provided  with  a  float  valve,  in  order  to  automatically  cut  off 
the  supply  when  the  water  reaches  proper  level.  If  the  city  pressure  is  not  high  enough, 
or  in  case  the  water  be  drawn  from  wells,  house  pumps  may  be  installed,  discharging 
into  the  surge  tanks.  Where  the  city  mains  are  provided  with  meters,  the  piping, 
before  it  enters  the  meter,  should  be  provided  with  a  screen,  to  remove  any  foreign 
substance. 

FEED-WATER   HEATERS. 

Feed-water  heaters  may  be  classified  as  exhaust  steam  heaters  and  economizers. 
Exhaust  steam  heaters  may  be  sub-classified  as  open  and  closed. 

Open  Heaters.  —  In  open  feed-water  heaters  the  water  is  heated  by  direct  contact 
with  the  steam.  This  may  be  accomplished  in  a  variety  of  ways,  by  a  spray,  over- 
flowing trays  or  an  umbrella.  If  there  is  sufficient  amount  of  exhaust  steam,  the  water 


FEED-WATER  HEATERS 


155 


may  be  heated  to  boiling  point.  However,  with  ordinary  power  plant  conditions, 
where  the  amount  of  exhaust  steam  supplied  by  the  auxiliary  machinery  is  but  a  small 
percentage  of  the  amount  of  steam  delivered  from  the  boilers,  this  high  temperature  is 
usually  not  obtained.  The  open  feed-water  heater  should  be  placed  at  least  four  to 
five  feet  above  the  boiler  feed  pump,  so  that  the  hot  water  will  flowr  by  gravity  to  the 
suction  valves,  whence  the  water  is  pumped  to  the  boilers.  Most  open  feed-water  heaters 


FIG.  i.     Stillwell  Open  Feed- Water  Heater. 

are  provided  with  an  oil  extractor  for  removing  oil  from  the  exhaust  steam,  so  that  it 
may  not  be  sent  to  the  boiler,  therefore  in  installing  an  open  feed-water  heater  sufficient 
clearance  should  be  left  for  the  removal  and  cleaning  of  the  filters  or  trays,  as  the  case 
may  be. 

Fig.  i  illustrates  a  Stillwell  open  feed-water  heater.  It  is  hardly  necessary  to 
describe  the  operation  of  this  heater,  as  it  is  clearly  depicted  in  the  illustration.  Other 
well-known  open  feed-water  heaters  are  the  Webster  and  Cochrane,  the  latter, 
which  is  especially  adapted  for  the  removal  of  oil,  is  shown  in  the  accompanying 
illustration. 


156  STEAM-ELECTRIC   POWER    PLANTS. 

Closed  Heater.  —  Closed  heaters  are  designed  for  carrying  the  exhaust  steam 
either  through  the  tubes,  or  surrounding  the  tubes.  In  the  former  the  shell,  which 
is  either  made  of  cast  iron  or  riveted  steel  plates,  must  be  of  considerable  thick- 
ness so  as  to  withstand  boiler  pressure,  provided  that  the  feed  pumps  discharge 
through  the  heater.  In  the  other  type  of  closed  heater  the  shell  may  be  made 
of  light  material,  as  it  withstands  no  pressure  other  than  that  of  the  exhaust 
steam. 


FIG  2.     Cochrane  Oil  Separator  on  Cochrane  Feed-Water  Heater. 

The  illustration  presented  above  shows  a  form  of  the  Cochrane  Oil  Separators,  ;'.  e.,  those  used  in 
connection  with  the  Cochrane  Feed-Water  Heaters.  As  these  Heaters  are  of  the  open  type,  in  which  the 
exhaust  steam  and  the  water  to  be  heated  are  brought  into  direct  or  actual  contact,  their  success  depends 
primarily  upon  the  efficiency  of  this  Oil  Separator. 

The  advantage  of  the  closed  heater  over  that  of  the  open  type  is  that  the  feed  water 
can  be  pumped  through  it,  thus  the  pump  handles  cold  water,  whereas  with  the 
open  heater  the  pumps  have  to  be  specially  fitted  for  hot  water.  Closed  heaters  have 


FEED-WATER  HEATERS. 


157 


to  be  provided  with  drains  and  mud  blow-offs,  the  drains  to  take  away  water  of  conden- 
sation and  oil  extracted  from  the  exhaust  steam,  the  mud  blow-offs  for  removing  the 
settlings  from  the  feed  water. 

All  heaters,  either  open  or  closed,  should  be  by-passed  with  sufficient  valves,  that 
is,  provision  should  be  made  so  that  the  exhaust  steam  may  pass  through  these  heaters 
or  directly  to  the  atmosphere.  The  heaters  may  also  be  provided  with  vent  pipes  con- 
nected to  the  atmospheric  exhaust  pipe  to  carry  away  air  and  vapor. 

As  already  stated  there  are  steam-tube  and  water-tube,  closed  feed- water  heaters; 
the  former  type  is  shown  in  Fig.  4,  which  represents  the  Otis.  An  arrangement  of 
water  tube  heaters  is  shown  in  Fig.  6.  In  this  cut  two  feed- water  heaters  are  con- 
nected to  the  exhaust  from  the  prime  mover  and  that  of  the  auxiliary  machines. 
This  arrangement  is  possible  in  small  installations  only,  and  will  operate  very  econom- 


FIG.  3.     Arrangement  of  Cochrane  Feed-Water  Heater  and  Vacuum  Oil  Separator. 

ically.  The  boiler  feed  water  is  first  brought  to  a  heater,  which  is  located  between 
the  engines  and  the  condenser,  the  water  may  be  heated  up  to  120°  Fahr.  if  26  inches 
vacuum  is  maintained  at  the  condenser.  This  26  inches  vacuum  does  not  extend 
all  the  way  back  to  the  engine,  as  the  loss  due  to  friction  may  amount  to  several 
inches,  depending  on  the  design  of  the  plant.  From  here  the  boiler  feed  water  passes 
to  the  auxiliary  heater,  which  receives  exhaust  steam  from  the  various  pumps,  raising 
the  water  to  210°  Fahr.  A  considerable  amount  of  condensing  water  .may  be  saved 
by  this  arrangement. 

Economizer.  —  The  location  of  the  economizer  depends  upon  the  design  of  the 
plant,  whether  the  smoke  flue  is  underground  or  overhead.  In  the  former  case  the 
apparatus  would  be  located  in  the  basement,  as  in  the  twin  municipal  light  and  power 
plants  at  Vienna,  while  in  the  latter  case  a  special  floor  is  required,  as  has  been  done 
in  the  St.  Denis  plant  at  Paris.  Very  frequently  the  economizer  is  placed  directly  in 
rear  of  the  boiler,  as  has  been  done  in  the  Chelsea  plant  of  London. 

The  economizer  should  be  placed  as  close  as  possible  to  the  boilers,  so  that  it  will 
receive  the  hot  gases  befcro  thoy  cool.  The  flue  connection  to  the  economizer  should 
be  provided  with  a  by-pass,  so  that  repairs  can  be  made  without  shutting  down.  Fig.  7 


158 


STEAM-ELECTRIC   POWER   PLANTS. 


represents  a  layout  of  the  Green  economizer  at  the  power  plant  of  the  Union  Rail- 
road Company,  at  Providence,  R.I.;  the  system  of  by-passing  may  readily  be  seen. 


EXHAusrlmi-rr  EXHAUST  |  OUTLBT 


FIG.  4.    Otis  closed  Feed- 
Water  Heater. 


FIG.  5.     Austin  Vacuum  Oil  Separator. 

Economizers  are  made  of  a  number  of  tubes  arranged  in  rows,  either  parallel  or 
staggered,  through  which  the  water  circulates.  They  are  usually  made  of  the  counter- 
current  type,  that  is,  the  hottest  gas  comes  in  contact  with  the  hottest  water  and  vice 


FEED-WATER  HEATERS. 


'59 


•versa.    As  soot  will  collect  on  a  cool  surface  very  readily,  scrapers  are  arranged  on 
each  tube  to  remove  this  deposit  as  fast  as  it  may  accumulate.     These  scrapers  are 


FIG.  6.     Arrangement  of  Primary  and  Supplementary  Heaters  in  connection  with 

Condensing  Engine. 

operated  in  groups  by  a  reversing  gear,  which  causes  them  to  travel  continuously  up 
and  down  the  tube. 

Owing  to  the  friction  of  the  gas  in  the  economizer,  and  also  to  the  low  temperature 


i6o 


STEAM-ELECTRIC   POWER   PLANTS. 


to  which  the  gases  may  be  reduced,  the  height  of  the  chimney  has  to  be  increased  from 
20  to  30  per  cent  over  that  where  no  economizer  is  employed.     In  order  to  overcome 


:::::::: 


FIG.  7.     Arrangement  of  Green  Economizers  for  Union  Railroad  Co.,  Providence,  R.  I. 


this,  mechanical  draft  may  be  installed,  and  at  the  same  time  the  stack  temperature 
may  be  reduced  to  300°  Fahr.  instead  of  450°  to  500°  Fahr.,  as  required  for  natural 
chimney  draft. 


FIG.  8.     Green  Economizer. 

Percentage  of  Gain.  —  Should  exhaust  steam  be  available,  the  latent  heat  should 
be  utilized  to  heat  the  boiler  feed  water,  either  in  an  open  or  closed  heater,  or  in  a 


FEED-WATER  HEATERS. 


TABLE    I.      PERCENTAGE    OF    SAVING    FOR    EACH    DEGREE    OF    INCREASE    IN 
TEMPERATURE    OF    FEED-WATER    HEATED. 


Pressure  of  Steam  in   Boiler,  Ibs.  per  sq  in.  above  Atmosphere. 


Initial 
Temp,  o 
Feed. 

O 

2O 

40 

60 

SO 

1OO 

120 

14O 

16O 

180 

20O 

Initial 
Temp. 

32° 

32° 

.0872 

.0861 

.0855 

.0851 

.0847 

.0844 

.0841 

.0839 

.0837 

.0835 

'.OSG3 

40 

.0878 

.0867 

.0861 

.0856 

.0853 

.0850 

.0847 

.0845 

.0843 

.0811 

.0839 

40 

50 

.0880 

.0875 

.0868 

\0864 

.0860 

.0857 

.0854 

.0852 

.0850 

.0848 

.0846 

50 

CO 

.0894 

.0883 

.0876 

.0872 

.0867 

.0864 

.0862 

.0859 

.0856 

.'C855 

.0853 

60 

70 

.0902 

'.0890 

.0884 

.0879 

.0875 

.0872 

.0869 

.0867 

.0864 

.0862 

.0860 

70 

80 

.0910 

.0898 

.0891 

.0887 

.0883 

.0879 

.0877 

.0874 

.0872 

.0870 

.0868 

80 

90 

.0919 

.0907 

.0900 

.0895 

.0888 

.0887 

.0884 

.0883 

.0379 

.0877 

.0875 

90 

100 

.0927 

.0915 

.0908 

.0903 

.0899 

.0895 

.0892 

.0890 

.0887 

.0885 

.0883 

100 

110 

.0930 

.0023 

.0916 

.0911 

.0907 

.0903 

.0900 

.0898 

.0895 

.0893 

.0891' 

110 

120 

.0945 

.0932 

.0925 

.0919 

.0915 

.0911 

.0908 

.0906 

.0903 

.0901 

,0899 

120 

130 

.0954 

.0241 

.0934 

.0928 

.0924 

.0920 

.0917 

.0914 

.0912 

.0909 

.0907 

130 

140 

.0963 

.0950 

.0943 

.0937 

.0933 

.0029 

.0925 

.0923 

.0920 

.0918 

.0916 

140 

150 

.0973 

0959 

.0951 

.0940 

.0941 

.0937 

.0934 

.0931 

.0929 

.0926 

.0924 

150 

160 

.0982 

.0968 

.0901 

.0955 

.0950 

.0946 

.0943 

.0940 

.0937 

.0935 

.0933 

160 

170 

.0992 

.0978 

.0970 

.0964 

.0959 

.0955 

.0952 

.0949 

.0946 

.0944 

.0941 

170 

180 

.1002 

-.0988 

.0981 

.0973 

.0969 

.0965 

.0961 

.0958 

.0955 

.0953 

.0951 

180 

190 

.1012 

.0998 

.0989 

.0983 

.0978 

.0974 

.0971 

.0968 

.0964' 

.0962 

.0960 

190 

200 

.1022 

.1008 

.0999 

.0993 

.0988 

.0984 

.0980 

.0977 

.0974 

.0972 

.0969 

200 

210 

.1033 

..1018 

.1009 

.1003 

.0998- 

.0994 

.0990 

.0987 

.0984 

.0981 

.0979 

210 

220 

.1029 

.1019 

.1013 

.1008 

.1004 

.1000 

.0997 

.0994 

.0991 

.0989 

220 

230 

.1039 

.1031 

.1024 

.1018 

.1012 

.1010 

.1007 

.1003 

.1001 

.0999 

230 

240 

-.1050 

.1041 

.1034 

.1029 

.1024 

.1020 

.1017 

.1014 

.1011 

.1009 

240 

250 

.1062 

.1052 

.1045 

.1040 

.1035 

.1031 

.1027 

.1025 

.1023 

.1019 

250 

162 


STEAM-ELECTRIC   POWER   PLANTS. 


storage  tank,  provided  with  coils,  whence  the  water  may  be  pumped  through  the  econo- 
mizer, thus  not  only  removing  certain  stresses  from  the  economizer,  but  also  improving 
the  efficiency  of  the  plant.  The  efficiency  of  an  economizer  is  frequently  claimed  to 


TABLE    II.      PERCENTAGE    OF    SAVING    EFFECTED    BY    HEATING    FEED-WATER 
FROM    INITIAL    TO     FINAL    TEMPERATURE. 


BOILER  GAUGE  PRESSURE  100  POUNDS 


INITIAL 
TEMPERATURE 

FINAL  TEMPERATURE   OF   WATER 

o 
o 

o 

o 

o 

10 

o 

00 

0 

o 

o 

M 

o 

0 

co 

N 

0 

« 

O 

0 

ID 

o 

0 
00 

o 
a\  _ 

o 
o 
co 

60 

3-5 

S-2 

6.9 

.8.6 

10.4 

12.  1 

13.0 

13.8 

14.7 

'S-5 

16.4 

17-3 

18.1 

19.0 

19.8 

20.7 

80 

1.7 

3-5 

c.2 

7.0 

8.8 

10.5 

11.4 

12.3 

13-2 

14.0 

14.9 

I5.S 

16.7 

'7-5 

18.4 

'9-3 

IOO 

o 

1.8 

3-6 

5-4 

7.1 

8.9 

9.8 

10.7 

11.6 

12.5 

13-4 

14-3 

15.2 

16.1 

17.0 

17.9 

no 

0.9 

2.7 

4-5 

6.3 

8.1 

9.0 

9-9 

10.8 

11.7 

12.6 

T3-5 

14.4 

'5-3 

1  6.2 

17.1 

1  20 

o 

1.8 

3-6 

5-5 

7-3 

8.2 

9.1 

IO.O 

10.9 

ii.S 

12.7 

,3.6 

'4-5 

15-5 

16.4 

130 

0.9 

2.8 

4.6 

6.9 

7-4 

8.3 

9.2 

IO.I 

I  I.O 

11.9 

12.S 

13.8 

14.7 

15.6 

140 

o 

1.9 

3-7 

5-6 

6.5 

7-4 

8.4 

9-3 

IO.2 

11.  i 

12.  1 

13.0 

13-9 

14.9 

150 

0.9 

2.8 

4-7 

5.6 

6.6 

7-5 

8.4 

9.4 

10.3 

I  1.2 

12.2 

13-1 

14.0 

1  60 

o 

1.9 

3-8 

4-7 

5-7 

6.6 

7.6 

8.5 

9-5 

10-4 

II-4 

12.3 

13.2 

170 

I.O 

>9 

3,8 

4.8 

5-7 

6.7 

7,6 

8.6 

9-5 

10-5 

11.5 

12.4 

1  80 

0 

1.9 

2.9 

3-9 

4.8 

•5.8 

6.8 

7-7 

8.7 

9-7 

10.6 

1  1.6 

190 

I.O 

1.9 

2.9 

3-9 

4.9 

5.8 

6.8 

7-8 

8.8 

9-7 

10.7 

200 

o 

.1.0 

2.O 

-3-0 

3-9 

4.9 

5-9 

6.9 

7-9 

8.9 

9.8 

205 

0.5 

i-S 

2-5 

3-5 

4.9 

5-4 

4.0 

4-5 

4-9 

6.4 

2IO 

o 

•5 

I.O 

2.0 

30 

4.0 

5.0 

6.0 

7.0 

8.0 

be  from  10  to  20  per  cent  according  to  the  temperature  of  the  gas  escaping  from  the 
boilers.  In  many  instances  it  has  been  proven  that  with  an  economizer  boiler  feed 
water  has  been  obtained  up  to  250°  Fahr.  The  percentage  of  gain  resulting  from  the 


SUPERHEATERS.  163 

increase  of  temperature  of  the  feed  water,  either  in  an  economizer  or  heater  in  any 
particular  case,  can  be  easily  calculated  by  the  following  formula: 

100  (T  -  t) 

Gam  per  cent  =  — TT 

rl  —  t 

Where  H  =  total  heat  of  steam  at  boiler  pressure  reckoned  from  o°  Fahr. 
T  =  temperature  of  feed  water  after  heating, 
t  =  temperature  of  feed  water  before  heating. 

It  will  be  seen  from  this  that  the  higher  the  exhaust  steam  or  flue  temperature  to 
be  utilized,  the  greater  is  the  gain. 

The  preceding  table  I,  gives  the  percentage  of  saving  for  each  degree  of  increase 
in  temperature  of  feed  water  heated,  calculated  with  the  above  formula. 

SUPERHEATERS. 

Classification.  —  In  order  to  produce  superheated  steam,  additional  heat  must  be 
applied  to  dry  steam.  This  may  be  accomplished  by  installing  a  special  apparatus, 
either  in  the  boiler  setting  or  in  a  separate  setting  having  its  own  furnace.  A 
number  of  small  superheaters  installed  in  each  individual  boiler  are,  of  course,  more 
expensive,  as  regards  first  cost,  than  a  few  large  superheaters  in  separate  settings.  It 
is,  however,  difficult  to  install  a  separately  fired  superheater,  owing  to  the  arrangement 
of  the  boiler  room,  and  the  difficulty  of  handling  coal  and  ashes;  besides  this  the  pipe 
connections  are  more  complicated.  An  advantage  of  the  separately  fired  superheater 
is  that  it  may  be  placed  close  to  the  prime  mover,  decreasing  the  loss  of  heat  in  the 
piping.  The  temperature  may  be  equally  controlled  in  each  type.  With  the  use  of 
"boiler  setting  or  flue  superheaters"  no  additional  space  is  required,  the  operating 
force  will  be  reduced,  as  the  stokers  attend  to  the  boiler  and  superheater,  and  the  pipe 
connections  are  simplified. 

The  superheater  itself,  as  will  be  seen  later,  may  be  classified  in  two  types,  namely, 
a  fire-tube  heater,  similar  to  a  tubular  boiler,  where  the  gases  of  combustion  pass 
through  tubes  surrounded  by  steam,  and  a  steam-tube  type,  where  steam  passes 
through  the  tubes  surrounded  by  hot  gases;  these  superheaters  may  again  be  sub- 
classified  as  cast-iron  and  steel-tube  type. 

Material.  —  Cast  iron  is  not  used  to  any  great  extent  in  the  construction  of  super- 
heaters, although  there  have  been  many  introduced;  the  difference  in  temperature  of 
the  steam  in  the  tubes  and  the  flue  gases  causes  their  quick  destruction. 

One  type  of  cast-iron  superheater,  the  Schwoerer,  however,  has  met  with  success; 
it  is  made  of  some  secret  alloy  of  cast  iron.  This  type  of  superheater  was  one  of  the 
earliest  and  is  largely  used  in  the  southern  part  of  Germany  and  Austria.  Ernst,  in 
a  report  to  the  "  Engineering  Congress  of  the  International  Society  of  Boiler  Inspectors," 
at  Zurich  in  1902,  states  that  in  the  district  of  the  Vienna  Boiler  Inspection  and  Insur- 


1 64  STEAM-ELECTRIC   POWER  PLANTS. 

ance  Society,  which  included  599  power  plants,  equipped  with  superheaters,  20.2  per 
cent  were  of  cast  iron,  while  99  per  cent  of  these  were  of  the  Schwoerer  type;  14  per  cent 
of  the  599  were  of  the  separately  fired  type. 

In  the  northern  part  of  Germany  steel  superheaters  are  in  use  exclusively;  one 
report  shows  that  in  nine  boiler  inspection  districts  not  a  single  cast-iron  apparatus 
was  employed.  It  will  be  easily  understood  that  common  cast  iron  cannot  withsfand 
the  differences  in  temperature;  for  instance,  Ripper  reports  in  the  Minutes  of  Pro- 
ceedings of  the  Institute  of  Civil  Engineers  that  with  a  steam  temperature  of  340°  Fahr., 
the  pipe  shell  temperature  was  610°,  or  a  difference  of  270°  Fahr.  As  this  test  was 
made  on  a  wrought-iron  superheater,  the  difference  of  temperature  in  a  cast-iron  super- 
heater will  be  still  greater.  Besides  this  in  modern  power  plant  practice,  with  the 
production  of  temperature  from  650°  to  750°  Fahr.,  the  difference  in  temperature  will 
be  greatly  increased. 

There  is,  however,  a  great  advantage  in  a  cast-iron  superheater,  provided  that  the 
alloy  is  a  proper  one.  As  this  type  of  superheater  is  made  up  of  extended  surface  and 
the  material  is  correspondingly  heavy,  the  shell  stores  a  greater  amount  of  heat  than  a 
steel  type  superheater  and  is,  therefore,  not  so  readily  affected  by  the  cold  draft  when 
opening  fire  doors,  and  a  more  even  temperature  of  steam  is  obtained.  This  type  of 
superheater  may  be  used  with  equal  advantage,  either  with  a  hand-fired  or  mechanical 
stoker  furnace. 

Steel  superheaters  are  much  more  readily  adaptable  to  the  available  space  in  the 
boiler  setting,  and  a  greater  heating  surface  may  be  obtained  in  a  smaller  space  than 
with  one  of  cast-iron  type.  The  steel  superheater  is  also  cheaper  and  easier  to  repair, 
as  there  are  no  special  parts  and  any  machine  shop  may  do  the  work.  As  a  light  steel 
shell  is  very  sensitive  to  change  in  temperature,  the  thickness  of  the  walls  of  the  tubes 
should  be  heavier  than  the  pressure  requires,  to  add  to  the  durability  and  economy  of 
the  superheater.  For  this  purpose  nickel-steel  tubes  have  been  introduced,  but  owing 
to  high  first  cost  they  have  not  been  favored. 

Cross-Section.  —  In  order  to  keep  the  steam  as  near  the  hot  gases  as  possible,  the 
tubes  are  made  either  small,  with  extended  surface,  or  with  an  inner  tube.  The  accom- 
panying'illustration,  Fig.  i,  shows  a  number  of  styles  of  tubes,  both  of  cast  iron  and 
of  steel.  The  upper  left-hand  illustration  shows  the  Schwoerer  type,  these  tubes  have 
an  internal  diameter  of  7^  inches.  They  are  provided  with  ribs  both  inside  and  out- 
side, the  inside  ribs  running  longitudinally  and  the  outside  radially,  thus  forming  a 
large  absorbing  surface  as  well  as  a  large  radiating  surface.  The  other  two  upper 
illustrations  also  show  cast-iron  tubes,  the  first  with  a  straight  division  wall  running 
through  the  center  of  the  tube  to  a  point  near  the  end,  so  as  to  create  a  circulation  as 
shown  by  the  arrows,  while  the  second  type  is  provided  with  a  spiral  division  wall, 
which  gives  the  steam  a  rotary  motion. 

The  lower  illustrations  show  superheaters  of  various  types  made  of  steel  or  similar 
material,  the  first  one  being  a  simple  tube  of  from  ij  inches  to  3  inches  in  diameter; 
this  is  the  one  most  commonlv  used.  The  thickness  of  these  tubes  varies  from  £  inch 


SUPERHEATERS. 


I65 


to  I  inch.  The  next  illustration  represents  the  Adorjan  tube,  which  is  4^  inches  out- 
side diameter.  In  order  to  reduce  the  cubical  contents  an  inner  tube  is  inserted,  this 
inner  tube  contains  still  air.  This  design  is  practically  the  same  as  that  of  the  Foster, 
with  the  exception  that,  in  the  case  of  the  latter,  the  inner  tube  is  larger,  giving  less 
cubical  contents  and  a  higher  temperature  with  the  same  amount  of  heating  surface; 
the  outer  surface  is  extended  similarly  to  the  Schwoerer  type. 

The  next  represents  the  Cruse  controllable  superheater.  The  outside  diameter  of 
the  large  tube  is  6  inches,  while  the  inner  tube  is  2  inches.  This  inner  tube  contains 
water  (boiler  feed)  instead  of  air,  as  in  the  former  types.  The  principal  object  of  this 


'52,3- 


FIG.  i.      Sections  of  Superheater  Tubes. 

type  of  superheater  is  to  control  the  amount  of  superheat  by  means  of  the  boiler  feed 
water.  If,  for  instance,  a  small  amount  of  steam  be  used  and  the  liability  arises  of  the 
superheater  becoming  overheated,  the  circulation  of  water  is  increased. 

The  last  illustration  shows  a  very  efficient  type  of  superheater  tube,  which  is  made 
in  two  different  sizes,  viz.,  \\  inches  and  2f  inches  diameter.  These  tubes  are  made 
in  the  boiler  works  of  B.  Meyer  in  Gleitwitz,  Germany.  It  consists  of  a  steel  spiral 
cross  rolled  in  a  plain  steel  tube.  These  spiral  crosses  not  only  give  the  steam  a  high 
rotation,  but  also  increase  the  radiating  surface  55  per  cent.  The  crosses  are  set  at 
one  complete  turn  per  meter  (3.28  feet).  As  these  crosses  are  not  inserted  in  the  bends, 
the  steam  will  revolve  thirty  to  forty  revolutions  per  minute.  The  efficiency  of  these 
tubes  is  from  40  per  cent  to  50  per  cent  higher  than  a  straight  tube.  Its  disadvantage 
is  the  high  cost  of  manufacture.  This  apparatus  is  especially  adaptable  to  a  boiler 


1 66  STEAM-ELECTRIC  POWER  PLANTS. 

where  but  a  limited  space  can  be  given  to  the  superheater,  and  where  a  high  degree  of 
superheat  is  desired. 

Circulation  of  Steam  and  Flow  of  Gases.  —  The  circulation  of  steam  in  a  super- 
heater varies  with  the  design,  as  is  indicated  in  Fig.  2.     The  form  varies  from  straight 


FIG.  2.     Forms  of  Superheaters. 

pipe  to  multiple  return  bends  and  spiral  coils.  Whatever  type  of  superheater  may  be 
adopted,  care  should  be  taken  that  there  are  no  rigid  connections,  so  that  expansion 
will  be  easily  provided  for ;  further,  that  the  tubes  contain  no  water  pockets.  Where, 
however,  such  conditions  exist,  proper  drains  should  be  installed.  The  apparatus 
should  be  designed  and  placed  so  that  the  collection  of  soot  will  be  minimized,  as 
soot  will  greatly  decrease  the  efficiency.  Soot  is  a  very  poor  conductor,  and  the  experi- 
ments made  by  Ernst  show  that  one  square  meter  (10.7  square  feet)  transmitting  per 
hour  3,000  calories  (1,191,000  B.T.U.)  will  require  in  addition  46°  C.  (115°  Fahr.)  if 
one  millimeter  (^V  inch)  of  soot  covers  the  pipes  of  the  superheater.  Therefore  the 
superheater  should  be  so  located  that  it  is  readily  accessible,  so  that  it  may  be  cleaned 
at  frequent  intervals.  This  is  doubly  important  with  such  types  of  superheaters  as 
will  collect  and  hold  a  large  amount  of  soot. 

The  superheater  should  be  designed  and  located  in  the  boiler  so  that  it  will 
absorb  the  greatest  amount  of  heat.  The  tubes  should  be  staggered. 

As  shown  in  the  accompanying  illustration,  Fig.  3,  there  are  three  systems,  parallel 
current,  counter  current  and  a  combination  of  same.  The  first  illustration  represents 
a  parallel  current,  while  the  second  one  represents  a  counter  current;  it  will  be  observed 
that  in  the  latter  case  the  hottest  gas  comes  in  contact  with  the  hottest  steam,  thus 


SUPERHEATERS. 


167 


materially  increasing  the  efficiency  of  the  apparatus.     The  theoretical  efficiency  of  the 
former  to  the  latter  is  as  1:1.158. 

Owing  to  the  fact  that  the  delivery  temperature  of  the  steam  in  the  counter-current 
type  is  at  times  too  high  and  is  subject  to  fluctuation,  a  combination  of  these  two  types 
is  used.  This  is  shown  in  the  following  two  illustrations,  the  first  of  which  is  parallel 
and  counter  current,  while  the  second  (shown  in  lower  left-hand  corner)  is  counter  and 


\ 

T      T 

\             \ 

T         f 

\ 

N 

11                    3 

\            ^ 

*                    3 

\ 

C 

\            ^ 

C 

\ 

\ 

3 

\            \ 

3 

^ 

N 
\ 

C 

\            \ 

( 

^ 

\ 

3 

\            \ 

3 

I 

\ 

C 

^            \ 

( 

\ 
\ 

\ 
\ 

3 

\            \ 

3 

\ 

\ 
\ 

\            \ 

C                    „ 

\ 
\ 
V 

t     f 

^nt 

f     f 

\ 

t 

t 

^ 

\ 
\ 

\ 

r              3 

c 

3 

Ih'   >                             II 

\ 
\ 

\ 

3 

C 

v                     } 

;.   t 

f 

\ 

\ 

t     f 

\ 

\ 

11                     3 

( 

j 

C 

«• 

> 
J 

11                    3 

C 

3 

C                    } 

A              1 

\ 

f 

1 

\ 

( 

^^ 

\ 

3 

\ 
\ 

( 

^  —  -  M 

3 

—  •-   \ 

) 

\ 

( 

\ 

3 

N 

( 

^) 

\ 

N 

f 

\ 

I    t 


FIG.  3.     Flow  of  Gases  and  Steam  in  Superheaters. 

parallel.  The  next  illustration  shows  a  double  counter-current  type.  In  this  type 
the  steam  first  passes  through  the  hottest  gases,  returning  as  shown  and  passing  through 
the  cooler  gases.  In  all  of  these  systems  the  flow  of  steam  is  at  right  angles  to  the  flow 
of  gas.  Superheaters  of  this  style  are  used  in  Europe.  The  last  illustration  is  the  type 
almost  exclusively  used  in  America  and  also  to  a  large  extent  in  Europe.  This  type 
is  a  counter-parallel  superheater. 

Controlling  Temperature. — There  are  various  devices  for  controlling  the  temper- 
ature of  superheated  steam;  viz.,  regulating  the  amount  of  flue  gases  passing  through 
the  superheater,  mixing  saturated  steam  with  superheated  steam,  injecting  a  fine  spray 
of  water  into  the  superheated  steam,  or  by  water  or  air  cooling. 


i68 


STEAM-ELECTRIC   POWER   PLANTS. 


For  regulating  the  amount  of  gas  passing  through  the  superheater,  butterfly  dampers 
may  be  installed,  so  that  all  of  the  gases  may  pass  over  the  superheater  or  only  a  desired 
percentage.  Fig.  4  represents  a  design  of  this  character.  It  will  be  seen  that  any 
amount  of  gases  desired  may  be  passed  over  the  apparatus,  or  it  may  be  cut  out  entirely 
in  case  the  superheater  breaks  down,  in  which  case  the  boiler  could  still  be  used,  supply- 
ing saturated  steam.  These  superheaters,  which  are  of  the  Buettner  type,  are  also 
installed  without  dampers,  in  which  case  the  shell  of  the  tubes  is  of  heavy  material, 
so  as  to  stand  the  high  temperature  before  steam  is  raised.  The  amount  of  superheat 
will  then  be  controlled  by  mixing  saturated  with  superheated  steam. 


Fig.  4.     Buettner  Superheater. 

Another  system  of  temperature  control  is  that  given  in  Fig.  5,  representing  a  sepa- 
rately fired  superheater,  which  is  designed  and  operated  as  follows:  The  tubes  of  the 
superheater  are  located  in  two  chambers  separated  by  a  division  wall,  the  furnace  being 
in  one  section  and  the  throttling  damper  in  the  other  section.  In  the  lower  row  of  tubes, 
connected  to  the  header,  are  inserted  steam-tight  tubes,  which  are  closed  at  one  end 
while  the  other  end  connects  with  a  small  separate  header.  These  tubes  are  filled 
with  air,  which,  with  an  increased  temperature,  operates  on  a  small  cylinder  filled 
with  glycerine,  provided  with  a  float,  which  in  turn  operates  the  well-balanced  throttling 
damper,  thus  regulating  the  amount  of  air  under  the  furnaces,  and  changing  the  char- 
acter of  the  furnace  gas.  The  massiveness  of  this  superheater  setting  will  also  be 
noticed,  which  prevents  undesirable  radiation.  For  the  same  purpose  both  headers 
of  this  superheater  are  kept  in  a  chamber  apart  from  that  conducting  the  furnace  gas. 


SUPERHEATERS. 


169 


I/O 


STEAM-ELECTRIC   POWER   PLANTS. 


It  will  be  noticed  in  the  right-hand  illustration  that  the  furnace  is  constructed  with  a 
heat-storage  chamber,  so  that  the  opening  of  the  fire  door,  admitting  cold  air,  will  not 
cause  a  fluctuation  in  the  temperature  of  the  steam. 

By  injecting  a  fine  spray  of  water  into  the  superheated  steam  at  a  point  where  it 
leaves  the  superheater,  any  desired  temperature  may  be  obtained ;  but  owing  to  the  low 


FIG.  6.     Cruse  Controllable  Superheater. 

conductivity  of  superheated  steam  the  water  may  not  be  entirely  evaporated  and  may, 
therefore,  be  carried  along  into  the  prime  movers.  This  system  of  controlling  the 
temperature  is,  therefore,  not  favored  very  much. 

A  system  controlling  the  temperature  of  superheated  steam  by  water  is  the  Cruse, 
and  is  designed  and  operated  as  follows:  a  water  branch  is  taken  from  the  boiler  at 


SUPERHEATERS.  171 

low  water  level,  and  water  is  drawn  out  at  this  branch  and  forced  through  two- inch 
copper  pipes,  which  traverse  the  superheater  pipes  from  end  to  end  and  return  to  the 
boiler.  Thus  each  end  of  this  copper  pipe  is  exposed  to  boiler  pressure,  and  to  force 
water  through  it  only  demands  energy  sufficient  to  overcome  the  friction,  which  is  not 
great  in  a  solid  drawn  copper  pipe.  To  produce  the  flow  the  water  is  passed  through 
an  inspirator  fed  with  superheated  steam.  When  superheated  steam  touches  water 
it  at  once  becomes  saturated,  and,  at  usual  temperatures  of  superheat,  it  loses  say 
20  per  cent  of  its  volume.  This  reduction  of  volume  is,  like  the  condensation  in  an 
ordinary  injector,  the  source  of  energy,  and  serves  to  propel  the  water  through  the 
inner  tubes  at  a  considerable  velocity.  Should  the  gases  become  hotter  and  the  steam 
temperature  rise,  its  volume  increases,  and  the  action  of  the  inspirator  is  correspond- 
ingly intensified.  More  water  flows  and  picks  up  more  heat  from  the  surrounding 
steam.  In  this  way  the  control  exercised  by  the  water  columns  is  automatic,  the  result 
being  that  the  temperature  of  superheat  varies  between  narrow  limits  and  the  danger 
point  is  never  reached.  This  Cruse  controllable  superheater  is  shown  in  the  accom- 
panying illustration,  Fig.  6.  The  apparatus  in  this  case  is  located  in  the  rear  of  a  flue 
boiler. 

Instead  of  having  water  circulating  through  the  inner  tube  of  the  superheater  for 
the  purpose  of  controlling  the  temperature,  air  may  be  circulated  through  same,  as 
is  done  in  the  Adorjan  superheater.  This,  as  previously  stated,  is  practically  the 
same  as  that  of  the  well-known  Foster  superheater,  an  illustration  of  which  is  given 
in  the  chapter  on  boilers,  with  the  difference  that  in  the  latter  type  the  air  is  stationary, 
and,  therefore,  not  controllable.  The  temperature  of  the  steam  in  the  Foster  system 
may  be  controlled  by  mixing  saturated  with  superheated  steam. 

Velocity  of  Steam.  —  The  velocity  of  the  steam  in  the  superheater  depends  entirely 
on  the  design  and  pressure  used,  and  should  be  such  as  not  greatly  to  reduce  the  pressure 
due  to  friction.  In  a  superheater  having  small  tubes  the  steam  may  travel  at  a  higher 
velocity  than  in  one  having  large  tubes,  because  the  heating  surface  is  distributed  more 
economically  per  unit  of  steam.  Where  steam  is  used  at  a  pressure  above  150  pounds 
a  fall  in  the  pressure  of  from  four  to  five  pounds  is  the  maximum  that  should  be  allowed, 
while  with  a  pressure  below  150  pounds  the  drop  should  not  exceed  three  to  four 
pounds.  In  a  test  reported  by  Berner  on  a  superheater  of  the  counter-parallel  type, 
as  illustrated  at  the  left  hand  of  Fig.  3,  the  drop  in  pressure  was,  in  the  counter-current 
part  of  the  superheater,  3.5  pounds,  while  in  the  parallel-current  side  of  the  superheater 
the  drop  was  2.5  pounds,  making  a  total  loss  of  6  pounds.  The  pressure  under  which 
this  test  was  carried  on  was  215  pounds,  while  the  diameter  of  the  tubes  was  i|  inches; 
the  velocity  in  the  tubes  of  the  counter-current  side  was  45  feet  per  second,  while  in 
the  parallel-current  side  the  velocity  was  66  feet  per  second. 

Low  velocities  are  used  in  certain  types  of  "fire-tube"  superheaters,  amounting  to 
from  13  to  20  feet  per  second.  In  the  greater  number  of  superheaters,  velocities  of 
from  40  to  60  feet  per  second  are  used,  while  in  some  types,  for  instance,  the  spiral 
cross  superheater,  velocities  up  to  90  feet  per  second  may  be  employed. 


STEAM-ELECTRIC   POWER   PLANTS. 


Size.  —  There  is  no  fixed  formula  that  can  be  given  for  calculating  the  size  of  a 
superheater,  as  there  are  too  many  items  to  be  taken  into  consideration,  such  as  the 
design  of  the  apparatus,  or  if  counter  or  parallel  flow,  etc. 

A  superheater  made  up  of  small  tubes  and  located  in  the  setting  of  water-tube 
boilers  needs  a  heating  surface  of  from  10  per  cent  to  12  per  cent  of  that  of  the  boiler 
to  secure  a  steam  temperature  (total)  of  from  460°  to  500°  Fahr.;  while  a  heating 


FIG.  7.  Goehring  Boiler 
and  Superheater  ;  the 
Heating  Surface  of  the 
Latter  is  50%  of  that 
of  the  Former. 


surface  of  20  per  cent  of  that  of  the  boilers  will  give  a  temperature  of  approximately 
570°  to  600°  Fahr.  If  the  heating  surface  of  the  superheater  is  one-third  that  of  the 
boiler,  the  temperature  will  be  about  660°  Fahr.  Superheaters  of  this  size  are  not  in 
use  at  present  in  America  or  England,  but  there  are  many  in  service  on  the  Continent 


SUPERHEATERS.  1/3 

of  Europe,  in  fact  there  are  a  number  which  run  as  high  as  50  per  cent.  The  accom- 
panying illustration,  Fig.  7,  shows  a  superheater  of  this  size  installed  in  a  water-tube 
boiler;  under  ordinary  operating  conditions  750°  Fahr.  may  be  easily  obtained. 

All  the  above  figures  are  based  on  practical  experience,  where  the  boiler  pressure 
is  from  175  to  225  pounds. 

The  amount  of  coal  required  to  superheat  steam  varies  with  the  design  and  loca- 
tion of  the  superheater  and  the  temperatures  of  the  steam.  The  specific  heat  of  super- 
heated steam  varies  with  the  temperature.  Regnault  determined  the  specific  heat  of 
superheated  steam  at  atmospheric  pressure  to  be  0.48,  but  more  recent  investigation 
shows  that  this  varies,  as  for  instance,  with  100°  superheat  the  specific  heat  is  0.65, 
while  it  is  0.75  for  200°. 

The  following  table,  based  on  the  above  figures  and  an  experiment  made  by  the 
Stirling  Consolidated  Boiler  Co.  with  their  superheater,  as  published  by  the  latter  in 
"A  Book  on  Steam  for  Engineers,"  may  be  of  interest: 

COAL   NEEDED   FOR   SUPERHEATING. 

DEGREES  OF  SUPERHEAT.  ADDITIONAL  COAL  NEEDED. 

75°  5  per  cent 

100°  7 

150°  ii        " 

200°  15  " 

250°  20  " 

These  data  are  not  given  here  to  show  an  increased  coal  consumption  for  super- 
heated steam,  for  with  the  use  of  superheated  steam  it  is  required  that  less  water  be 
evaporated  than  would  be  the  case  if  saturated  steam  were  employed.  This  fact 
more  than  counterbalances  the  amount  of  coal  required  to  superheat,  provided  proper 
prime  movers  have  been  selected.  For  the  same  reason  the  size  of  the  boiler  may 
be  reduced. 

Types.  —  There  are  a  great  number  of  different  types  of  superheaters  on  the  market, 
some  of  which  have  been  illustrated  in  the  chapter  on  boilers  and  also  in  the  begin- 
ning of  this  article.  The  Foster  and  Babcock  &  Wilcox  superheaters  have  already 
been  mentioned.  The  former  is  constructed  of  steel  tubes,  with  extended  surfaces 
formed  of  cast-iron  rings,  forming  a  heavy  mass,  which  gives  a  large  storage  capacity 
for  heat,  thus  reducing  the  fluctuation  of  temperature  in  the  steam.  The  Babcock  & 
Wilcox  apparatus  is  of  the  small  tube  type,  with  arrangement  to  flood  same  in  order 
to  protect  the  tubes  before  steam  is  raised.  There  is  a  disadvantage  in  flooding  a 
superheater  if  the  water  used  is  dirty  or  impure,  as  it  will  scale  the  tubes;  these  tubes 
cannot  very  well  be  cleaned,  and  they  will  have  to  be  removed  and  replaced.  If  this 
is  not  done  the  efficiency  of  the  superheater  will  be  decreased. 


174 


STEAM-ELECTRIC   POWER   PLANTS. 


Another  type  of  small  tube  superheater  is  given  in  Fig.  8,  illustrating  the  Watkin- 
son  system.  This  superheater,  as  illustrated,  is  not  separately  fired,  but  is  separately 
set,  being  located  in  the  boiler  flue  path.  Arrangement  may  be  made  to  by-pass,  so 


FIG.  8.     Watkinson  Superheater. 


that  any  amount  of  gas  may  be  sent  through  the  setting  or  it  may  be  cut  out  entirely. 
This  same  superheater  may  be  separately  fired  or  arranged  in  the  boiler  setting. 

A  cast-iron  superheater  which  is  successfully  used  on  the  Continent  of  Europe  is  the 
Schwoerer,  shown  in  Fig.  9.  In  this  particular  case  the  superheater  is  separately  fired 
and  consists  of  fourteen  tubes.  As  the  tubes  are  vertical,  provision  is  made  to  drain 
each  tube. 

A  fire-tube  superheater  is  shown  in  Fig.  10.  This  type  of  construction  is  new, 
although  its  principle  rests  upon  one  of  the  earlier  superheater  systems,  namely,  a  long 
cylindrical  chamber,  in  which  were  inserted  tubes  conveying  the  steam,  while  the  hot 
gases  surround  them  in  the  chamber.  This  newer  type  (Heizmann),  as  will  be  seen, 
is  aflat  box,  of  only  i£  inches  thickness  over  all,  through  which  two-inch  tubes  are 
passed  in  staggered  rows,  expanded  into  the  sides;  while  the  hot  furnace  gases  pass 
through  these  tubes,  the  steam  in  passing  through  the  box  is  deflected  at  as  many 
points  as  there  are  tubes,  thus  thoroughly  mixing  it  and  producing  a  uniformly  high 
temperature. 


SUPERHEATED   STEAM. 


175 


A  similar  system  is  that  of  Pregardien.     In  this  system,  instead  of  having  the  box 
riveted  together  and  the  pipes  inserted,  the  entire  apparatus  is  welded  together  as 


ooooooooooo 

OOOOOOOOOO I 
OOO.OOOOOO'OOj 

OOOOOOOOOO 

1000,00000000 

OO'^OQOO4>OO   I 

OOO'OOOOO'OOOi 

OOOOOOOOOO ! 

ooooooooooo 

I    OOOOOOOOOO i 

IOOOOO4MDOOOOI 

OOOOOOOOOO  i 

'ooooooooooo 

!    OOOOOOOOOO i 
iOOOiOOOOO,OOO! 

oo-4-oooo-^-oo  i 
loooboooo'oooi 

i    OOOOOOOOOO i 
'OOOOOOOOOOO 

OOOOOOOOOO 
iOOOOOOOOOOO 


FIG.  9.     Schwoerer  Separate  Fired  Superheater. 


FIG.  10.     Heizmann  Fire  Tube  Superheater. 


though  made  of  a  single  piece.  An  advantage  of  this  type  of  superheater  is  that  a  very 
high  temperature  may  be  obtained.  They  may  be  used  in  the  boiler  setting  or  separate 
fired  type. 

SUPERHEATED    STEAM. 

Saturated  Steam.  —  Steam  may  be  classified  as  live  and  exhaust  steam;  the  former, 
which  will  be  considered  under  this  heading,  may  be  sub-classified  as  saturated  and 
superheated  steam.  Saturated  steam  is  steam  at  the  temperature  of  the  boiling  point  of 
water  whose  temperature  depends  on  the  pressure.  Saturated  steam  may  be  either 
wet  or  dry.  The  former  is  steam  carrying  water  in  suspension  in  the  form  of  a  mist, 
while  the  latter  (dry  steam)  is  steam  containing  no  free  moisture. 

Practically  all  boilers,  when  not  equipped  with  a  special  device,  deliver  wet  satu- 
rated steam.  Zeuner  states  that  the  amount  of  water  carried  over  in  suspension  with 
the  steam  is  from  7^  per  cent  to  15  per  cent,  while  Hirn,  from  a  very  satisfactory  test, 


1 76 


STEAM-ELECTRIC   POWER   PLANTS. 


found  but  5  per  cent.     Experiments  conducted  on  various  Babcock  &  Wilcox  boilers 
showed  an  average  moisture  of  8.2  per  cent. 

The  properties  of  saturated  and  superheated  steam  are  frequently  required  in  cal- 
culating sizes  of  pipes,  etc.  In  the  following  table  the  specific  heat  of  superheated 
steam  has  been  taken  as  0.55. 

Superheated  Steam.  —  In  order  to  produce  superheated  steam  additional  heat 
must  be  added  to  dry  saturated  steam;  the  temperature  and  volume  will  be  increased 

TABLE    I.     PROPERTIES    OF    SATURATED    AND    SUPERHEATED     STEAM. 

(From  "  Steam,"  Babcock  &  Wilcox  Ltd.,  London.) 


PROPERTIES  OF  SATURATED  SxiiAM, 

TOTAL  HEAT  OH*  SUPKRHEATED  STEAM  FROM 

Partly  from  C.  H.  Peabody's  .Tables. 

WATFR  AT  32°  F     (Specific  heat,  0*55  B.T.U.) 

Superheat  in  degrees  Fahrenheit. 

Pressure  in 
pounds  per 

Pressure 

rernpera- 

fotalheat 

Heat 

Heat  of 

Density 

1  Factor  of 

pounds 

ture  in 

leat  units 

liquid 

tion,  or 

or  weight 

of  one 

lent 

per  sq.ui. 

Fahren- 

from 

from 

Intent 

ft.  in 

3ound  in 

evapora- 

steam 

\vacuum. 

heit. 

32°. 

units. 

heat  units 

pounds. 

at  212°. 

120° 

150" 

200° 

250° 

300 

gauge. 

I 
.2 

3 
4 
5 
6 

I 

9 

10 

'5 
20 

25 
3° 
35 
40 
45 
So 

g 

101-99 
126*27 
141*62 

162-34 

170-14 
176-90 
182-92 
188-33 

227-95 
240*04 
250*27 
259*19 
267*13 
274-29 
280*85 
286*89 

1113.1 
1,20*5 
1,25*, 
1128*6 
"SI'S 
"33'8 
"35-9 
H37;7 

1140*9 
1146-9 

1158-3 
11610 

"63-4 
1165*6 
1,67*6 
,169*4 
1171*2 

70  "o 

94'4 
109*8 
,21*4 

130-7 

138*6 

145-4 

'5'  "5 
156-9 
161*9 
181*8 
196*9 
295*1 
219*4 
228*4 
236-4 
243-6 
250*2 

256-3 
261*9 

I  °43'o 
1026*1 

1007*2 
1000*8 

99o45 
986*2 

982*5 
979*0 

965;! 
946*0 

932*6 

927*0 
922*0 
917-4 
9I3"1 
909*3 

0*00299 
0*00576 
0*00844 
0*01107 
0*01366 
0*01622 
0*01874 
002125 
0*02374 
0*02621 
0*03826 
0*05023 
0*06199 
0-07360 
0*08508 
0*09644 
0*1077 
0-1188 
0-1299 
0*1409 

334-5 

J73'6 
118*5 
90'33 
73'" 
61*65 

53-39 
47*06 
42*12 
38-15 
26*14 
,9*91 
16*13 
13-59 
11*75 
10*37 
9-285 
8*4,8 
7-698 
7-097 

•9661 
•9738 
•9786 
•9822 
•9852 
"9876 
•0897 
•9916 
"9934 
'9949 
1*0003 
1*005, 
1*0099 
1*0129 
1*0157 
1-0182 
i  '0205 
1*0225 
i  '0245 
i  '0263 

1179*1 
186*5 
191*1 
194*6 
197-5 
199.8 
20,  9 

205  4 
206  9 

212*9 

217-5 

221*1 

224-3 
227*0 
229*4 
231*6 

235H 
237*2 

*  195-6 
1203*0 
,207*6 

1214*0 
1216*3 
1218*4 
1  220*2 

1221*9 

1229*4 
1234*0 
1237-6 
I240'8 
1243-5 
1245-9 
1248*1 
1250'! 
1251-9 

«53'7 

,223', 
1230-5 
1235"! 

I2-1,S'6 

1241*5 

1243-8 
1245-9 
12477 

1250*9 
1256*9 
,261*5 

I26-j*I 

,268*3 

1271*0 
1273-4 
1275*6 
1277*6 
1279*4 
1281*2 

250*6 
258*0 
262*6 
266*1 
269*0 
27  1'  '3 

275'2 
2769 
278*4 
284*4 
289*0 
292*6 
295*8 
298*5 
300*9 
3°3  'o 

305-1 
306*9 
3087 

,278*1 
1285*5 
1290*1 
1293*6 
1296*5 

1300*9 

1302  7 
1  3°4  "4 
13059 
I3H'9 

1320*1 
1323'3 
1326*0 
,328*4 
I330'6 
I332-6 
1334-4 
1336-2 

i 

S 
10 

15 

20 

25 

30 

35 
40 

45 

65 
70 

75 
80 

85 

00 

i*  95 

100 

I05 
no 

"5 
120 

"5 
130 
140 
150 
,60 
,70 
180 
190 
200 
225 
250 
275 
300 
325 
350 
375 

297*77 
302-7, 
307-38 
311-80 
316*02 
320*04 
323-89 
327-58 

334-56 

337]86 

344'i3 

347-12 

358*26 
363-40 
368*29 

377-44 
381-73 
391-79 
400*99 
409-50 
417*42 
424*82 

431-9° 
438*40 

1172*7 
1  174'3 
"75'7 
1177*0 
1178*3 
1179*6 
1180-7 
1181*9 
1182*9 
1184*0 
"85-0 
1186*0 
1186*9 
1187*8 
1189*5 

:  1191*2 
1192*8 

I:95'7 
1197*1 
198*4 
201-4 
204*2 
206-8 
209*3 
211-5 
213-7 

267*2 
272*2 
276*9 
281*4 
285*8 
290*0 
294-0 
297-9 
301*6 

308*7 
3,2*0 
S'S'2 
318*4 
3Z4-4 
33o-o 
335'4 
340-5 
345  'ft 

354'6 
365-1 
!  374'7 
383-6 
39"<-9 
399-6 
406*9 
414*2 

9°5'5 
902*1 

892*5 

889*6 
886*7 
884*0 
881*3 
8788 
876*3 
874-0 
871-7 
869*4 
865*1 
861*2 
857-4 
853-8 
850-3 
847-0 
843-8 
836-3 
829-5 
823-2 
817-4 
811-9 
806*8 
801*5 

0*1519 
0*1628 

0*1843 
0*1951 
0*2058 
0*2165 
0*2271 
0-2378 
0*2484 
0*2589 
0*2695 
0*2800 
0*2904 
°'3™3 
0*3321 
0-353° 
o*3737 
0*3945 
o*4"<53 
o*4359 
0*4876 
"'5393 

0-644 
0-696 
0*748 
0*800 

6*58-5 
6-143 
5'76o 
5-426 
5-126 

t'859 
4*619 
4-403 
4*205 
4*026 
3*862 

•J'571 
3'444 

3*212 

3*o,i 
2-833 
2-676 

2-535 
2*408 
2*294 
2*051 
1-854 
1*691 
i  '553 
i"437 
'"337 
1-250 

1*0280 
i  '0295 
i  *o-*og 
1-0323 
10337 
1-0350 
i  '0362 

••'0385 
1*0396 
1*0406 
1*0416 
,  '0426 
1-0435 
i'o453 
,  '0470 
1*0486 
f  1*0502 
1-0517 
1-0531 
1  "°545 
1*0576 
1*0605 
1*0632 
1*0657 
1*0680 
,  '0703 
i  '0724 

240*3 
241-7 
243-0 

z44]3 

246-7 
247-9 
248-9 
250-0 
251-0 
252-0 
252-6 
253-8 
255-5 
257-2 
258*8 
260*3 
261*7 
263*1 
26.1*4 
267*4 
270*2 
272*8 
275-3 
277'S 
279*7 
281*7 

1255-2 
1256*8 
1258*2 

1259-5 
1260*8 
1262*1 
1263*2 
1264*4 
1265*4 
1266  5 
1267-5 
1268-5 
1269"! 
1270-3 
1272*0 
1273-7 
1275-3 
1276-8 
1278*2 
1279  6 
1280*9 
1283*9 
,286*7 
1289*3 
1231*8 
1294*0 
1296*2 
,298*2 

,284*3 

1285*7 

1287*0 

1288*3 

,289*6 
,280-7 
1291-9 
1292*9 

1294*0 
1295-0 

1  296*0 
1296  6 
1297*8 
12995 
1301*2 
1302*8 
1304-3 
1305-7 
IS0?  i 
1308*4 
13-1-4 
,3,4*2 
,316*8 

1321-5 
1325-7 

310*2 

311*8 

3-4-5 

1318*2 

13194 
1320*4 
13215 
1322-5 

1324.1 
1325-3 
1327*0 

,328*7 

1330-3 

133  '-8 
1333-2 
1334,6 
i335'9 
1338-9 
I34I-7 
i344'3 
1346*8 
1.349-0 

1351   2 

i?53'2 

"337  7 
1339^3 

,342*0 
13433 
i  344  '6 
1345-7 
1346.9 

1347-9 
I349;o 

135';° 

13,2*8 
13545 

1357-8 

1359-3 
1360*7 
1362  I 
1363-4" 

1366-4 

1369*2 

13743 

=376-5 
1378-7 
1380*7 

5° 

io 

6S 
70 

e 

85 
90 

95 

too 

'05 

1  10 

1*5 
T35 
'45 

'55 
165 
175 
•85 

210 

235 
260 
285 

310 

335 

400 
500 

445'i5 
466*57 

224*2 

421-4 
444'3 

796-3 
779-9 

0*853 
1-065 

1-172 
'939 

i  -°745 
1*0812 

283*7 
290*2 

1300*2 
1306-7 

'334  "2 

3B 

1389*2 

485 

without  varying  the  pressure.     There  is  no  fixed  formula  to-day  to  determine  the 
relation  of  the  increase  in  volume  to  the  increase  in  temperature.     For  practical  use  the 


SUPERHEATED   STEAM. 


177 


Zetmer  formula,  although  not  absolutely  accurate,  is  used  in  Europe  and  found  fairly 
satisfactory. 

It  is  as  follows: 

PlVl  «  R  (t,  -  273)  -  Cptn 

in  which 

/>!  =  Pressure  of  steam  in  kg.  per  sq.  cm.  absolute  (14.7  Ibs.  per  sq.  in.). 
/t  =  Temperature  of  superheat  (Centigrade). 
v,  =  Additional  volume  in  cubic  meters. 

R,  C  and  n  are  constants,  which  for  p  are  expressed  in  kilogram  per  square  centimeter 

and  for  v  in  cubic  meters. 


R  =  0.00509 


C  =  0.193 


The  accompanying  curve  chart,  Fig.  i,  has  been  plotted  from  the  above  formula 
and  converted  into  the  English  system.     From  this  chart  it  is  easy  to  calculate  the  size 


230 
220 
210 
2oo 

Ul 

h     I9o 

£     I8° 
8     170 

<     ICO 
*      ,50 

g     "" 

lio 

BE 
UJ      120 

a 

110 

m    loo 

_j 

90 
80 

to 
io 

1 

~i~i 

\ 

\\ 

\ 

A 

\ 

\\ 

VOLU  ME          OF 

SUPERHEATED          STEAM 
FRANK         KOESTER 

"STEAM  -ELECTRIC  POWER-PLANTS" 

\ 

A 

V 

i 
\ 

V 

A 

\ 

\ 

\ 

\\ 

\  \ 
\ 

\ 

\ 

\ 

>. 

V 

V 

\ 

\\ 

* 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

\ 

V 

\ 
\ 

\ 
\ 

\ 

$ 

\ 

\ 

\ 

s 

\ 

^ 

\ 

\ 

\ 

\ 

\ 

\v 

\ 

\ 

\ 

s 

\ 

s 

\ 

\ 

\ 

\ 

S 

\ 

\ 

\ 

X 

s 

% 

^ 

e. 

^ 

\ 

y 

^ 

^ 

t^ 

da.q. 

.     1 

F. 

total 

T€  Hi  f 

• 

v 

\ 

X 

\ 

"V 

^ 

^ 

^ 

S 

-Ch 

i 

S  6          7  8 

CU.     FT.      PER      tB. 

Fig.  i. 


10 


12. 


of  a  pipe  required  to  transmit  a  certain  volume  of  steam.  For  instance,  assume  an 
absolute  steam  pressure  of  185  pounds  and  a  total  temperature  of  550°  Fahr.  (175°  Fahr. 
superheat)  the  volume  will  be  3  cubic  feet  per  pound  (saturated  steam  being  2.45 
cubic  feet  per  pound).  In  order  to  transmit  1,000  pounds  of  steam  per  minute  at  a 


1/8 


STEAM-ELECTRIC   POWER   PLANTS. 


velocity  of,  say,  6,000  feet  per  minute,  a  pipe  area  of  77  square  inches  (10  inches  diam- 
eter) will  be  required. 

A  still  more  convenient  and  fairly  accurate  table  was  presented  by  Mr.  Foster 
before  the  American  Society  of  Mechanical  Engineers,  May,  1907.     By  the  courtesy 


S8S 
176- 
165 
25? 
2H5 
1SF 
US 

*>s 

log 

V'95 

I     185 

a  ITS- 

*     165 
*    155 

*    its 
0.   ias 

rtr 

•i 

*i"* 

^     105 

«       »5 
^      «* 

75" 
45 
55 

*T 
ptvMitt. 
£.000  ft.  . 

c^..inc)|. 
g  .     ^  . 

\  \ 

\ 

V 

n 

\ 
1 

\\ 

A 

X1 

V 

4ii 

-* 

\ 

\ 

d 

A 

\ 

j 

V 

\ 

r 

3 

L       ' 

A 

\ 

V 

\ 

f 

0? 

\ 

r 

\ 

\ 

0 

\ 

\t 

V 

\ 

\ 

\ 

\ 

C 

V 

A 

sN 

A 

ftl 

><7^ 

i 
^ 

\ 

\ 

\ 

\ 

\ 

\ 

v^ 

^s 

sxN 

§ 

\ 

36 

<r* 

\\ 

\\ 

\N 

^ 

.S 

^ 

\ 

NS 

\  ( 

S^1 

^ 

^ 

»\ 

^ 

ro~ 

^ 

P\ 

$ 

^ 

v.xs 

\\ 

\ 

\ 

?°1 

S*1 

x\ 

^ 

V 

s\ 

\ 

i 

Ctl 

V 

*> 

s^i 

\v 

N\ 

\^ 

N 
\ 

\ 

\  \ 

\ 

:\ 

X    > 

\ 

N\ 

^X   S 

\' 

s\ 

3 

551 

K^ 

s 

s 

X 

o 

ss 

Ns 

^ 

h  +, 

<^ 

?  f 

\ 

s 

§ 

vs 

\v 

sS 
rf^l 

& 

2 

^-. 

3 

^0 

5~*- 

\ 

^S 

x 

^ 

"X 

N-jf 

2 

Jo  • 

^ 

^ 

•^ 

^ 

| 

ifl 

•*N 

\^ 

^> 

Vni 

% 

^i 

^ 

^," 

^ 

• 

^ 

^> 

^  ^ 

^3 

At 
X^ 

<!i 

^h 

^* 

^1 

^ 

^ 

•^. 

•r> 

•^s 

39 

o^ 

"*^ 

"^ 

£ 

^ 

**~a 

« 

^ 

*r», 

**»i 

MO 

s^ 

^4 

3 

ii 
DO 

r* 

Ss, 
•—  , 

>*, 
-K- 

•>-*, 

•^« 

5a 
•^» 

,?  . 

fi  • 

7    . 

2    • 

2  1 

9   b 

i  f. 

}  f. 

&  i. 

1    t 

6  i. 

6    >• 

7   1- 

3   I 

9  1 

0  1. 

1    3 

}  f- 

^  p. 

i  * 

5  i 

i   i 

*  a. 

B  % 

r  i 

8.000  - 

If 

.|« 

£ 

•1? 

h 

2 

tk 

ill 

| 

%  ' 

l|> 

'I 

1 

£ 

'U 

J 

7     1 

k 

ik 

t\ 

»  ] 

|i 

ili 

10,000  •  . 

\ 

.1- 

IT 

t> 

•h 

•la 

<» 

•|c 

I- 

>• 

I 

* 

h 

i 

s 

,\i 

/.|r 

t 

Area    jier    s^uave    inch     r  «.  «}  u  •  v  «_  d     io    pas*    i.Ooo       lb& 
of  &tc.«m     y»«.r     hoof     «»    6,  8  ,  <  IO,OOO  f  1.  p  cr    min. 

FIG.  2. 

of  Mr.  Foster,  this  chart  has  been  used  in  Fig.  2.  The  chart  gives  the  area  required 
in  square  inches  to  pass  1,000  pounds  of  steam  per  hour  at  a  velocity  of  6,000,  8,000 
and  10,000  feet  per  minute. 

Much  has  been  written  during  the  past  few  years  regarding  the  great  advantage 
in  the  use  of  a  high  degree  of  superheated  steam,  especially  has  this  been  done  by 


SUPERHEATED   STEAM.  179 

continental  writers.  This  may  be  justified,  for  continental  engineers  have  a  broader 
experience  on  this  subject.  They  point  out  the  remarkable  results  obtained  by  the 
use  of  steam  superheated  to  5  50°  or  650°  Fahr.  and  even  as  high  as  700°  to  750°  Fahr. 
(400°  C.),  the  latter,  however,  not  being  everyday  practice.  They  are  right  from 
their  point  of  view,  for  manufacturers  on  the  Continent  guarantee  results  to  this  effect, 
their  prime  movers  being  designed  to  operate  satisfactorily  with  this  degree  of  super- 
heat. The  trouble  still  existing  in  America  with  certain  prime  movers,  when  supplied 
with  steam  of  a  total  temperature  of  500°  to  480°,  and  even  lower,  is  that  the  prime 
movers  fail  or  other  trouble  ensues.  It  must,  however,  be  admitted  that  owing  to  the 
superior  skill  of  some  manufacturers,  such  troubles  are  not  universal. 

Of  course  a  prime  mover  operating  under  higher  temperatures  and,  therefore, 
with  a  higher  efficiency  is  more  expensive,  thus  reducing  the  profit  to  the  manufacturer 
on  this  class  of  apparatus,  for  he  is  obliged  to  sell  in  competition  at  the  same  price  as 
other  manufacturers.  However,  the  ulitmate  result  is  that  the  manufacturer  of  the 
high-grade  prime  movers  sells  more  of  his  manufacture,  as  amply  proven  during  the 
last  few  years. 

Owing  to  these  conditions,  the  highest  degree  of  superheat  actually  adopted  for 
American  and  English  power  plant  practice  is  1 50°  to  1 70°  Fahr.  or  a  total  temperature 
of  530°  to  550°.  With  the  above  prime  movers  in  use,  it  is  best  to  supply  a  lower  degree 
of  temperature  in  order  to  avoid  trouble  in  the  operation  of  the  plant,  since  it  must 
be  borne  in  mind  that  the  higher  the  temperature  the  greater  the  liability  to  leakage, 
break-down,  etc.,  which  is  especially  true  with  prime  movers  not  especially  designed 
for  a  high  degree  of  superheat. 

The  tendency  during  the  past  two  years,  probably  after  some  manufacturers  had 
discovered  the  injurious  effect  of  the  high  degree  of  superheat  on  their  engines,  is  to 
advocate  the  use  of  still  lower  degrees  of  temperatures  than  those  which  would  be  most 
efficient,  claiming  that  equally  good  results  can  be  obtained  by  100°  of  superheat  as 
by  200°. 

Eminent  French  and  German  engineers,  specialists  and  authorities  on  the  subject 
state  differently,  although  some  still  maintained  ten  years  ago  that  there  is  no  possible 
increase  in  the  use  of  temperatures  above  550°  Fahr.  But  since  that  tiihe  prime  movers 
have  been  built  to  stand  a  higher  degree  of  temperature,  so  that  engines  and  turbines 
are  sold  to-day  on  the  Continent  to  work  at  10  and  9  pounds  per  I.H.P.  hour 
and  even  less.  The  governing  conditions,  however,  in  this  country  are  somewhat 
different  from  abroad,  owing  to  the  difference  in  cost  of  fuel,  which  in  Europe  is  prac- 
tically double,  and  for  which  reason  the  American  manufacturer  may  seem  justified  in 
producing  only  such  prime  movers  as  will  operate  under  moderate  temperatures  of 
superheat.  It  must,  however,  be  borne  in  mind  that  the  ultimate  aim  in  the  design 
of  power  plants  ought  to  be  the  reduction  to  a  minimum  of  cost  of  production  of 
a  K.W.,  and  in  order  to  do  so  a  high  degree  of  superheat  is  essential. 


CHAPTER  V. 
PIPING. 

Introductory.  —  This  subject  is  the  most  important  part  of  the  design  of  the  power 
plant,  after  the  general  arrangement  of  the  machinery  has  been  laid  out.  The  suc- 
cessful, economical  and  convenient  operation  of  the  plant  depends  largely  on  the  system 


1 

.79 

1.77 

16 

201.06 
213.83 

31 

754.76 
779.31 

46 

1661.91 
1698.23 

61 

y* 

2922.47 
2970.58 

76 

4536.47 
4596.36 

91 

6503.90 
6575.56 

2 

>4 

3.14 
4.90 

17 

226.98 
240.53 

32 

y* 

804.25 
829.57 

47 

1734.95 
1772.06 

62 

3019.08 
3p67.97 

77 

4656.64 
4117.31 

92 
X 

6647.65 
6720.08 

3 
X 

7.06 
9.62 

18 

254.47 
268.80 

33 

855.30 
881.41 

48 
X 

1809.56 
1847.46 

63 

3117.25 
3166.93 

78 

4778.37 
4839.83 

93 

6792.92 
6866.16 

* 

12.56 
15.90 

19 

283.53 
,298.65 

34 

907.92 
934.82 

49 

1885.75 
1924.43 

64 

3217.00 
3267.46 

79 

4901.68 
4963.92 

94 
X 

6939.79 
7013.82 

5 

X 

19.63 
23.75 

20 
X 

314.16 
330.06 

35 

962.11 
989.80 

50 

1963.50 
2002.97 

65 

3318.31 
3369.56 

80 

1A 

5026.56 
5089.59 

95 

7088.23 
7163.04 

6 

28.27 
33.18 

21 

346.36 
363.05 

36 

1017.  S7 
1046.34 

51 

2042.83 
2083.08 

66 

3421.20 
3473.24 

81 

5153.01 
5216.82 

96 

7238.25 
7313.84 

X 

38.48 
44.17 

22 

380.13 
397.61 

37 

K 

1175.21 
1104.46 

52 

2123.72 
2164.76 

67 

3525.66 
3578.48 

82 

5281.03 
5345.63 

97 

7389.83 
7466.21 

8 

50.26 
56.74 

23 

415.48 
433.74 

38 

1134.11 
1164.16 

53 

2206.19 
2248.01 

68 

3631.69 
3685.29 

83 
X 

5410.62 
5476.01 

98 
X 

7542.98 
7620.15 

9 

X 

63.61 

70.88 

24 

452.39 
471.44 

39 

1194.59 
1225.42 

54 

2290.23 
2332.83 

69 

3739.29 
3793.68 

84 

5541.78 
5607.95 

99 
X 

7697.71 
7775.66 

10 

X 
11 

12 
13 
14 
15 

78.54 
86.59 

95.03 
103.87 

113.10 
122.72 

132.73 
143.13 

153.94 
165.13 

176.72 
188.69 

25 
26 
27 
28 
29 

30 
X 

490.88 
510.71 

530.93 
551.55 

572.56 
593.95 

615.75 
637.94 

660.52 
683.49 

706.86 
730.62 

40 
41 

42 

43 
X 

44 

45 
K 

1256.64 
1288.25 

1320.25 
1352.65 

1385.45 
1418.63 

1452.20 
1486.17 

1520.53 
1555.29 

1590.43 
1625.97 

55 

56 
X 

57 
58 
59 
60 

2375.83 
2419.23 

2463.01 
2507.19 

2551.76 
2596.73 

2642.09 
2687.84 

2733.98 
2780.51 

2827.44 
2874.76 

70 
71 
72 
73 

74 
75 

3848.46 
3903.63 

3959.20 
4015.16 

4071.51 
4128.26 

4185.40 
4242.93 

4300.85 
4359.17 

4417.87 
4476.98 

85 

86 

87 

>/* 

88 
89 
90 

5674.51 
5741.47 

5808.82 
5876.56 

5944.69 
6013.22 

6082.14 
6151.45 

6221.15 
6291.25 

6361.74 
6432.62 

100 

% 

7854.00 
7932.74 

• 

FIG.  i.     Area  of  Circles. 

1 80 


HIGH-PRESSURE  PIPING.  l8l 

and  arrangement  of  pipes,  and  it  is  therefore  proper  that  a  great  amount  of  time  in 
designing  a  power  plant  should  be  spent  on  this  subject. 

The  piping  may  be  divided  under  two  headings,  high-  and  low-pressure.  The  former 
wrill  consist  of  main  and  auxiliary  steam  piping,  boiler  feed,  blow-off  and  drip  systems, 
while  the  latter  will  consist  of  exhaust  and  exhaust  drain  and  all  piping  in  connection 
with  the  condenser  system,  as  well  as  that  of  the  house  pumps,  fire  lines,  boiler  feed 
suction,  etc.  There  are  other  high-  and  low-pressure  pipings,  such  as  oiling  system 
which  will  be  treated  separately. 

Under  high-pressure  we  may  consider  pressure  from  125  pounds  to  250  pounds, 
while  the  low-pressure  will  include  anything  under  125  pounds. 


HIGH-PRESSURE   PIPING. 

Size  of  Pipes.  —  The  sizes  of  pipes  depend,  of  course,  on  the  character  of  steam 
to  be  used,  for  the  velocity  of  saturated  steam  transmitted  through  a  pipe  is  greatly 
reduced  by  friction,  while  superheated  steam,  being  a  rarer  medium,  is  not  so  easily 


.3 

Q 

% 

K 

i 

t* 

2 

atf 

3 

4 

5 

6 

7 

8 

9 

10 

a 

3 

~ 

2.27 

4.88 

'5-8 

3'-7 

52.9 

96.9 

2°5 

377 

620 

918 

1,292 

',767 

2,488 

3,0'4 

3,786 

4,904 

5,927 

7,321 

8,535 

9,7'7 

X 

y 

2.60 

2.05 

6.97 

14.0 

23-3 

42.5 

90.4 

1  66 

273 

405 

569 

779 

1,096 

',328 

1,668 

2,161 

2,615 

3.226 

3,76i 

4,282 

H 

I 

7-55 

2.90 

3-45 

6.82 

11.4 

20.9 

44-' 

81.  i 

'33 

198 

278 

380 

536 

649 

8'5 

1,070 

',263 

1,576 

',837 

2,092 

i 

«K 

24.2 

9-30 

3-20 

1.26 

3-34 

6.13 

13.0 

23.8 

39-2 

58.1 

8'  .7. 

112 

'57 

190 

239 

310 

375 

463 

539 

614 

'M 

2 

54.8 

21.  0 

7-25 

2.26 

1.67 

3-o6 

6.47 

11.9 

19.6 

29.0 

40.8 

55-8 

78.5 

95.1 

119 

»55 

'87 

23' 

269 

307 

2 

2M 

102 

39-4 

13.6 

.4-23 

..87 

1.83 

3-87 

7.12 

11.7 

'7-4 

24.4 

33-4 

47.0 

56.9 

7'-5 

92.6 

112 

138 

161 

184 

^A 

3 

170 

65-4 

22.6 

7-°3 

3-" 

1.66 

2.12 

3-89 

6-39 

9.48 

'3-3 

20.9 

23-7 

3'.  2 

39-' 

50.6 

61.1 

75-5 

88.0 

100 

3 

4 

376 

'44 

49-8 

'5-5 

6.87 

3.67 

2.21 

1.84 

3.02 

4.4» 

6.30 

8.61 

12.  I 

14.7 

18.5 

23-9 

28.9 

35-7 

4..6 

47-4 

4 

5 

686 

263 

90.9 

28.3 

'2-5 

6.70 

4.03 

1.83 

1.65 

2.44 

3-43 

4.69 

6.60 

8.00 

IO.O 

13-0 

'5-7 

'9-4 

22.6 

25.8 

5 

6 

1,1  16 

429 

.48 

46.0 

20.4 

'0.9 

6.56 

•2-97 

1.63 

1.48 

2.09 

2.85 

4.O2 

4.86 

6.ii 

7.91 

9.56 

11.8 

13-8 

•  5-6 

6 

7 

',707 

656 

226 

7°-5 

31.2 

16.6 

IO.O 

4-54 

2.49 

1.51 

1.41 

»-93 

2.71 

3-28 

4.12 

5-34 

6-45 

7-97 

9-3' 

10.6 

7 

8 

2,435 

936 

322 

IO1 

44-5 

23.8 

'4-3 

6.48 

3-54 

2.l8 

«-43 

«-3S 

'•93 

2-33 

2.92 

3-79 

4-57 

5.67 

6.60 

7-52 

8 

9 

3,335 

1,281 

440 

»37 

60.8 

32.5 

19.5 

8.85 

4.85 

2.98 

1.95 

'•37 

1.41 

1.71 

2.14 

2-77 

3-35 

4.14 

4.83 

5-5° 

9 

10 

4,393 

1,688 

582 

181 

80.4 

42.9 

25.8 

11.7 

6.40 

3-93 

2-57 

i.  80 

1.32 

1.  21 

1.52 

'•97 

2.38 

2-94 

3-43 

3-9' 

10 

11 

5,642 

2,168 

747 

233 

103 

55-' 

33-' 

'5-o 

8.22 

5.05 

3-3' 

2.32 

1.70 

1.28 

1.26 

1.63 

1.88 

2-43 

2.83 

3-22 

it 

12 

7,087 

2.723 

93& 

293 

129 

69.2 

41.6 

18.8 

10.3 

6-34 

4-  '5 

2.91 

2.  '3 

1.61 

1.26 

1.30 

'•57 

'•93 

2.26 

2.58 

12 

13 

8,657 

3-326 

1,146 

358 

158 

84-5 

50.7 

23-0 

12.6 

7-75 

5.07 

3-56 

2.60 

1.98 

'•53 

1.22 

1.21 

1.49 

'•74 

1.98 

13 

M 

10,600 

4,070 

',403 

438 

'93 

103 

62.2 

28.2 

15.4 

9-48 

6.21 

4-35 

3-18 

2.41 

1.88 

1.50 

1.22 

1.24 

1.44 

1.64 

'4 

i5 

12,824 

4,927 

1,698 

530 

234 

'25 

75-3 

34-' 

,8.7 

11.5 

7-52 

5-27 

3.85 

2.92 

2.27 

I.8l 

1.48 

1.  21 

1.17 

'•35 

IS 

16 

M,978 

5,758 

1,984 

619 

274 

146 

88.0 

39-9 

21.8 

'3-4 

8.78 

6.15 

4.51 

3-4' 

2.66 

2.12 

'•73 

1.42 

1.18 

1.14 

16 

17 

'7,537 

6,738 

2,322 

724 

320 

171 

103 

46.6 

25.6 

'5-7 

10.3 

7.20 

5-2? 

3-99 

3-" 

2-47 

2:03 

1.66 

'•37 

1.17 

18 

20,327 

7,810 

2,691 

840 

37' 

198 

119 

54.1 

29.6 

18.2 

11.9 

8-35 

6.  1  1 

4-63 

3.60 

2.87 

2-35 

1.92 

1-59 

1.36 

1.  16 

20 

26,676 

10,249 

3,532 

I,IO2 

487 

260 

'57 

70.9 

38.9 

23-9 

15.6 

10.9 

8.02 

6.07 

4-73 

3.76 

3.08 

2.52 

2.08 

1.78 

1.52 

24 

42,624 

'6,376 

5,644 

l,76l 

778 

416 

250 

I'3 

62.1 

38.2 

25.0 

'7-5 

12.8 

9.70 

7-55 

6.01 

4.92 

4.02 

3-32 

2.84 

2.43 

3° 

75,453 

28,990 

9,990 

3,  "7 

'-378 

736 

443 

201 

110 

67.6 

44-2 

31.0 

22.7 

17.2 

13-4 

10.7 

8.72 

7.14 

5.88 

5-°3 

4-3° 

36 

120,100 

46,143 

15,902 

4,961 

2,193 

1,172 

70S 

3'9 

'75 

108 

70.4 

49-3 

36.1 

27-3 

21.3 

16.9 

'3-9 

"•3 

9-37 

8.01 

6.85 

42 

'77,724 

68,282 

23,531 

7-34' 

3,245 

'.734 

1,044 

473 

259 

»59 

104 

73-0 

53-4 

40.5 

3«-5 

25.1 

20.5 

16.8 

«3-9 

11.9 

IO.  I 

48 

249,35' 

95,818 

33,02° 

10,30  1 

4,554 

2,434 

',465 

663 

363 

223 

146 

102 

75-o 

56.8 

44.2 

35-2 

28.8 

23-5 

19-4 

16.6 

14.2 

.a 
5 

X 

K 

X 

>l/2 

2 

2^ 

3 

4 

5 

6 

7 

8 

9 

10 

it 

12 

'3- 

14 

'5 

16 

>7 

ACTUAL   INTERNAL  DIAMETERS. 

FIG.  2.     Equation  of  Pipes. 

affected;  the  size  of  pipes  carrying  saturated  steam  must  be  larger  than  if  superheated 
steam  is  employed. 

A  curve  chart,  showing  the  increase  in  volume  of  superheated  steam  at  various 
pressures  and  different  temperatures,  is  to  be  found  in  the  chapter  on  superheated 
steam. 

Common  practice  is  to  use  a  velocity  of  from  6,000  to  7,500  feet  for  saturated  steam, 


I  82 


STEAM-ELECTRIC   POWER   PLANTS. 


while  for  superheated  steam  9,000  to  10,000  feet  and  higher  may  be  used,  this  depend- 
ing upon  the  amount  of  superheat. 

When  connecting  a  number  of  pipes  to  a  main  or  larger  pipe,  friction  should  be 
taken  into  consideration;  the  preceding  table  is  calculated  on  the  rating  of  the  actual 
areas  of  pipes  and  the  number  of  pipes  that  can  be  supplied  by  a  larger  one,  allowing 
for  friction,  the  lower  half  below  the  diagonal  blank  space  giving  the  actual  areas. 

In  order  to  calculate  the  fall  in  pressure  which  occurs  in  a  steam  pipe,  due  to  fric- 
tion and  which  is  increased  by  condensation,  the  following  formula,  given  by  Geipel, 
may  be  used: 


Q  =  3000 


P  = 


V  pd5D 


L 


Q2L 


9,000,000 


V  =  9170 


LD 


in  which 


d  =  Diameter  in  inches. 

L  =  Length  in  feet. 

p  =  Loss  in  pressure. 

D  =  Weight  of  steam  in  pounds  per  cubic  foot. 

Q  =  Pounds  of  stearn  per  hour. 

V  =  Velocity  in  feet  per  minute. 

In  using  this  formula,  the  number  of  bends  and  globe  valves  have  to  be  taken  into 
consideration,  and  allowance  made  for  them;  the  following  table  gives  the  amount  of 
this  allowance  for  standard  90°  bends: 


Diameter  of 
Pipe. 

Length  of  Straight  Pipe 
Allowed. 

2  inches 

6  feet  8  inches 

3       " 

10       "       0         " 

4       " 

13     "     4       " 

5       " 

16     "     8      " 

6       " 

20       "       0         " 

7      " 

23     "     4       " 

8       " 

26     "     8      " 

10          " 

33     "     4      " 

12          " 

40     "     o      " 

General  Consideration.  —  Among  the  most  radical  changes  in  power  plant  installa- 
tion, in  recent  years,  has  been  the  adoption  of  higher  pressures  and  higher  degrees  of 
superheat.  The  use  of  pressures  ranging  from  200  to  300  pounds,  accompanied  by 
temperatures  of  from  500°  to  750°  Fahr.,  has  made  necessary  the  design  and  use  of 
heavy  constructions  in  pipes,  fittings  and  flanges. 


HIGH-PRESSURE  PIPING.  183 

In  producing  superheated  steam  it  is  possible  to  increase  the  steam  temperature, 
and  at  the  same  time  keep  the  pressure  constant;  the  practice  to-day,  however,  tends 
towards  increasing  the  pressure  also,  and  the  time  is  not  far  distant  when  pressures  up 
to  250  pounds  will  not  be  considered  high.  There  are  in  operation  to-day,  particu- 
larly in  Germany,  a  number  of  plants  where  pressures  higher  than  225  pounds  are 
employed;  one  example  being  that  of  the  Technische  Hochschule  (University)  in 
Darmstadt,  where  the  plant  is  equipped  with  the  most  modern  boilers,  engines  and 
turbines,  the  steam  being  furnished  at  a  pressure  of  300  pounds  and  superheated  to 
750°  Fahr.  Although  this  plant  supplies  steam  for  various  prime  movers  and  heating 
purposes,  the  main  object  is  more  for  experimental  purposes  in  connection  with  the 
University.  Another  instance,  as  previously  stated,  where  some  300  pounds  pressure 
and  750°  Fahr.  superheated  steam  were  used  was  at  the  St.  Louis  Exposition  in  1904, 
where  a  Delaunay  Belleville  boiler  furnished  steam  to  a  6-cylinder,  quadruple  expan- 
sion, 1,500  horse-power  engine  of  the  same  make. 

The  use  of  steam  at  high  temperature  naturally  means  an  increase  in  the  expansion 
of  the  pipe,  and  the  use  of  high  pressure  demands  the  use  of  high-grade  material  and 
heavy  construction.  There  are  also  other  important  factors  which  must  be  considered, 
such  as  the  system  of  piping.  As  the  steam  line  is  in  reality  the  main  artery  of  the 
plant,  it  is  of  the  utmost  importance  that  it  be  so  designed  that  an  accident  to  a  portion 
of  it  will  not  result  in  shutting  down  the  entire  plant.  The  liability  of  rupture  may 
be  minimized  by  selecting  the  highest  grade  of  material  on  the  market^,  and  being,  sure 
that  the  system  adopted  for  the  main  steam  pipes  is  such  that,  in  case  of  a  failure,  a 
particular  section  may  be  cut  off,  and  steam  thrown  over  to  an  emergency  line.  In 
doing  so,  of  course,  care  must  be  taken  to  design  the  system  as  simple  as  possible,  and 
so  flexible  as  to  permit  of  any  section  being  cut  out  at  a  moment's  notice,  without  shut- 
ting down  the  adjacent  engines. 

System  of  Piping.  —  There  are  two  main  types  of  power  plants  in  general  use.  In 
one  of  these  the  engine  and  boiler  rooms  lie  parallel  to  each  other,  and  in  the  other  the 
boilers  are  arranged  at  90°  to  the  generating  room.  However,  there  are  other  plants 
installed  where  the  boilers  are  situated  at  the  end  of,  the  generating  room,  and  in  cer- 
tain instances  the  boilers  have  been  located  above  the  generating  room;  toth  layouts 
being  chosen  on  account  of  space  conditions.  This  same  consideration  also  governs 
to  a  great  extent  the  layout  of  the  pipe  system.  For  instance,  the  third  mentioned 
arrangement  of  boiler  and  generating  room  usually  requires  an  extremely  long  main 
steam  pipe.  Should  this  be  one  single  line  it  will  readily  be  seen  that  when  a  rupture 
of  a  pipe  connection  occurs  near  the  generating  room  it  will  result  in  shutting  down 
the  entire  plant.  Therefore  a  double  header  or  ring  system  may  be  advantageously 
employed.  In  the  other  mentioned  arrangements  the  single,  double  header,  or  ring 
system  may  be  used.  These  three  pipe  systems  are  shown  in  the  following  illustra- 
tions. 

The  single  header  system  usually  consists  of  a  line  run  at  the  back,  or  above  the 
boilers,  to  which  are  connected  the  lines  from  the  boilers,  the  connections  either 


184 


STEAM-ELECTRIC   POWER   PLANTS. 


entering  from  the  sides  or  dropping  from  above  the  main  header.  The  arrangement 
of  valves  is  such  that  any  boiler  may  be  easily  disconnected  from  the  header,  either 
automatically  or  by  hand.  The  steam  line  to  the  prime  movers  is  taken  from  this 
main  header,  usually  from  the  top,  in  order  to  prevent  the  condensation  which  may 
have  accumulated  in  the  header  from  entering  this  pipe. 

The  disposition  of  valves,  both  in  the  main  line  and  in  the  branches,  should  be  of 
a  character  to  insure  flexibility  of  operation  and  to  enable  the  steam  to  be  drawn  from 
any  or  all  of  the  boilers,  as  may  be  necessary,  and  so  that  the  line  of  any  engine  may 


BOILERS 


401- 


-KH- 


BOILERS 


-*0f 


•KK- 


ENGINES 


*04- 


ENG1NES 


FIG.  3.     Single  Header  System. 

be  disconnected.  The  general  character  of  this  single  header  system  is  shown  in 
Fig.  3,  and  on  account  of  the  extreme  simplicity  of  this  system  it  is  very  commonly 
used.  It  will  be  noticed  that  Fig.  3  shows  a  single  main  pipe  from  two  boilers  (one 
battery)  which  have  been  cross-connected,  leading  directly  to  the  main  header  from 
which  the  engine  is  supplied.  Only  a  few  valves  have  been  employed,  although  it 
might  be  easily  arranged  to  supply  the  adjacent  engine  from  this  battery,  or  even  a 
single  boiler.  The  fine  drawn  lines  throughout  the  figures  from  3  to  5  indicate  the 
steam-pipe  connections  to  and  from  the  superheaters,  which  are  placed  directly  in  the 
boiler  setting.  It  will  also  be  observed  that  valves  have  been  provided  to  cut  out 
the  superheater  and  use  saturated  steam. 

The  top  of  Fig.  3  shows  the  same  single  header  system,  with  each  boiler  having  a 


HIGH-PRESSURE  PIPING. 


I85 


separate  line,  [as  these  two  boilers  (one  battery)  supply  steam  for  one  engine,  and  as 
each  boiler  has  its  own  supply  pipe  to  the  header],  corresponding  arrangement  has 
been  provided  from  the  header  to  the  engine,  this  practice,  however,  being  rarely  used. 
The  multiple  header  system  consists  of  two  or  more  headers  to  which  the  connect- 
ing pipe  lines  from  the  boilers  are  joined,  and  from  which  branches  are  led  to  the 
engines.  The  general  arrangement  of  this  system  is  shown  in  Fig.  4,  and  from  these 
diagrams  it  will  be  seen  that  the  arrangement  is  a  very  flexible  one,  providing  as  far  as 
possible  against  interruption  of  the  service.  Two  possible  methods  of  cross-connec- 


BOILER5 


-M 


\    iy0*;. 

\JH: 


BOILERS 


-»o«- 


^V-" 


.«*•«-. 

fy 


-k» 


-•OH 


ENGINES 


FIG.  4.     Double  Header  System. 


tion  are  shown  in  this  illustration,  and  it  will  be  observed  in  the  upper  end  method 
that  flexibility  is  obtained  at  the  cost  of  numerous  valves  and  fittings.  It  is  apparent 
that  there  is  an  almost  infinite  number  of  ways  in  which  multiple  headers  may  be 
connected,  but  in  any  event  the  object  of  this  system  is  to  provide  an  extra  header  to 
carry  the  load  in  case  of  emergency,  and  the  best  method  of  cross- connecting  is  that 
which  requires  the  minimum  number  of  valves  and  fittings,  and  at  the  same  time  is 
the  most  flexible. 

The  general  arrangement  of  the  ring  system  is  shown  in  Fig.  5,  the  main  steam 
header  being  in  the  form  of  a  closed  ring,  which  may  be  split  into  sections  by  means 
of  suitably  placed  valves.  There  are  numerous  variations  possible  with  this  arrange- 
ment; e.g.,  where  the  header  runs  round  both  sides  of  the  boiler  room,  the  two  sections 


i86 


STEAM-ELECTRIC   POWER   PLANTS. 


may  be  cross- connected  at  desirable  points,  or  where  the  two  sections  of  the  ring  are 
close  together,  on  account  of  the  expansion  in  short  cross-connections,  the  rings  should 
be  closed  at  the  ends  by  means  of  flexible  bends.  Double  ring  systems  have  never 
been  employed,  because  the  single  header  has  been  found  to  answer  the  purpose  just 
as  efficiently,  and  without  the  unnecessary  complications  attached  to  the  previous 
mentioned  system.  However,  a  header  system  of  more  than  two  main  lines  has  been 
installed  in  the  5Qth  Street  power  house  of  the  Subway  system  of  New  York  City, 
where  some  60  boilers  and  9  main  engines  have  been  connected  by  a  3-header  system. 


FIG.  5.     Single  Ring  System. 


This  3-header  steam-pipe  system  was  installed  for  the  purpose  of  equalizing  the  steam 
pressure  of  the  entire  plant.  The  pipes,  which  arc  10  inches  in  diameter,  are  arranged 
one  above  the  other  in  a  so-called  separate  pipe  area.  As  this  plant  is  693  feet  long, 
it  will  be  readily  seen  that  a  large  amount  of  expansion  must  be  taken  up  in  these 
lines,  and  for  this  purpose  the  pipes  are  arranged  in  snake  lines.  At  the  junction 
of  an  1 8- inch  main  cross  steam  pipe  leading  from  a  group  of  six  6oo-horse-power  boilers 
is  placed  a  manifold.  At  the  junction  of  this  pipe  and  that  of  the  three  equalizing 
pipes  are  placed  valves,  to  cut  off  either  the  supply  pipe  from  the  boilers  or  either 
one  of  the  equalizing  pipes.  The  accompanying  illustration,  Fig.  6,  shows  this.  As 
these  pipes  are  some  20  feet  above  the  engine-room  floor  level,  and  as  the  pipe  con- 


HIGH-PRESSURE  PIPING. 

i 


FIG.  6.     Three-Header  Piping  System  (59111  St.  Plant,  New  York). 


i88 


STEAM-ELECTRIC   POWER   PLANTS. 


nections  to  the  engines  are  made  in  the  basement,  it  was  found  necessary  to  install 
long  vertical  risers  or  so-called  "steam  down-takes."  These  steam  down-takes,  it 
will  be  observed  in  the  illustration,  appear  in  goose-neck  form  in  order  to  take  up 
the  expansion  and  contraction  of  the  pipes.  A  quick  closing  valve  has  been  placed 
above  the  before-mentioned  manifold,  and  may  be  operated  from  a  distance  in  case 
of  emergency,  thus  shutting  off  the  two  main  down-takes  connecting  to  one  engine. 
These  illustrations  are  taken  from  an  article  by  the  author  which  appeared  in  The 
Engineer  of  December,  1904. 

Expansion. — As  already  pointed  out,  proper  means  must  be  provided  for  taking 
up  expansion  and  contraction  of  all  pipe  lines,  without  any  excessive  strain  on  the 
fittings.  In  modern  practice  the  expansion  is  of  great  importance,  on  account  of  the 
use  of  high  degrees  of  superheat.  Take,  for  example,  a  line  carrying  dry  saturated 


FIG.  7.     Cast-Iron  or  Semi-Steel  Anchor. 

steam  of  175  pounds  gauge  pressure  (377°  Fahr.),  the  same  steam  superheated 
150°  Fahr.,  as  is  commonly  employed  in  America  and  Great  Britain,  would  have  a 
total  temperature  of  527°  Fahr.,  and  assuming  a  temperature  of  some  90°  or  100°  either 
above  the  boiler  or  in  the  pipe  trenches,  wherever  the  pipes  may  be  placed  it  would 
give  a  difference  in  temperature  of  430°  Fahr.  The  expansion  due  to  this  430°  Fahr. 
has  to  be  taken  up  in  the  expansion  allowance  of  the  pipe  system.  The  calculation 
of  the  expansion  of,  say,  one  hundred  feet  of  pipe  may  be  easily  accomplished  by  the 
following  data:  for  each  i°  Fahr.  in  difference,  the  expansion  will  be  .000x3067  of  an  inch 


HIGH-PRESSURE  PIPING. 


189 


per  inch,  or  approximately  .00008  of  an  inch  per  foot.  A  more  convenient  form 
of  this  data  for  one  working  with  a  number  of  pipe  lines  at  a  given  temperature  is 
to  reduce  the  coefficient  so  as  to  apply  to  ten-foot  pipe  lengths,  which  for  the  above 


Competition 


FIG.  ya.     Swivelling  Joint  for  High-Pressure  Steam. 


temperature  (430°  Fahr.)  is  .34  inch.  This  constant  applies  to  wrought  iron  or  steel, 
while  the  coefficient  of  cast  iron  is  .0000059  per  degree  Fahrenheit  per  unit  of  length. 
As  the  difference  is  so  small,  the  coefficient  for  wrought  iron  is  usually  employed. 

AncHors.  —  In  order  to  have  the  expansion  equally  distributed  over  the  piping, 
it  is  of  importance  properly  to  locate  the  anchors;  these  anchors  are  not  only  installed 


190 


STEAM-ELECTRIC   POWER   PLANTS. 


on  account  of  expansion,  but  to  minimize  the  vibration  of  the  piping  and,  therefore, 
they  should  be  placed  where  the  vibration  is  the  greatest.  Anchors  are  designed 
usually  to  suit  a  particular  condition,  and  are  either  bolted  direct  to  the  structural 
steel  or  tied  by  rods  and  turn-buckles.  The  accompanying  illustrations  show  some 


c 

D 

Q 

I 

FIG.  8.     Pipe  Anchor. 

types  of  anchors;  Fig.  7,  representing  an  anchor  consisting  of  a  tee,  with  a  foot  cast 
on,  so  that  it  can  be  bolted  direct  to  the  steel  work,  or  to  the  wall  t6  suit  the  conditions, 
while  Fig.  8  shows  one  made  entirely  of  wrought  iron,  and  composed  of  two  bands  of 
flat  iron  tied  together  on  the  back  with  a  distance  piece.  Two  tie-rods  are  employed 
to  pull  apart  these  bands  and,  the  more  they  are  pulled  apart,  the  tighter  the  clamp 

ANCHOR 


FIG.  9.     Location  of  Anchor. 

will  hold.     This  anchor  is  cheap  and  simple,  yet  efficient,  and  will  serve  practically 
for  any  anchorage. 

Where  long  "U"  bends  are  installed  to  take  up  the  expansion,  the  author  would 
suggest  to  locate  the  anchor  in  .the  middle  of  the  bend,  as  shown  in  Fig.  9,  in  which 
case  either  of  the  above  anchors  may  be  employed. 

Supports  and  Hangers. — As  there  are  only  a  few  anchors,  the  remainder  of  the 
piping  must  be  supported  either  .by  means  of  brackets  or  hangers.  It  is  impossible 


HIGH-PRESSURE  PIPING. 


191 


here  to  state  how  far  apart  these  hangers  or  supports  are  to  be  placed,  but  they  should 
be  in  sufficient  number  to  take  any  strain  off  the  flanges  of  the  piping.  Where  fittings, 
valves,  etc.,  increase  the  weight  of  the  pipe  line,  hangers  or  supports  should  be  placed, 
not  only  on  account  of  the  increased  weight,  but  also  of  the  increased  vibration  at  these 
points. 

Hangers  are  usually  made  of  a  wrought-iron  band,  in  halves,  clamped  around  the 
pipe  and  suspended  by  a  rod  and  turn-buckle  from  any  convenient  point.  In  case  the 
pipe  has  to  be  supported  from  below,  cast-iron  or  structural  steel  brackets  may  be 
employed.  These  brackets  are  frequently  provided  with  roller  bearings,  as  seen  in 


i 


FIG.  10.     Bracket  with  Adjustable  Roller  Bearing. 

some  of  the  accompanying  illustrations.  Fig.  10  shows  a  bracket  with  adjustable 
roller  bearing  as  manufactured  by  the  Walworth  Manufacturing  Company,  while  the 
two  upper  brackets,  shown  in  Fig.  u,  as  manufactured  by  the  Crane  Company, 
have  brackets  with  a  roller  attached  and  one  with  the  pipe  strapped  down  to  the 
bracket;  the  latter  illustration,  Fig.  n,  shows  a  number  of  features  applicable  to 
various  arrangements.  Frequently  supports  are  required  for  vertical  risers;  an  ex- 
ample of  such  is  shown  in  Fig.  12,  a  number  of  which  were  installed  in  the  59th 
Street  power  house  of  New  York.  Where  expansion  or  contraction  has  to  be  taken 
care  of  in  a  riser,  proper  means  must  be  provided,  either  by  a  spring  system  or  a 
counterbalanced  system  to  allow  for  same.  A  type  of  the  latter  is  .shown  in  Fig.  13, 
which  has  been  installed  in  the  University  plant  at  Darmstadt,  Germany.  It  will  be 
seen  that  the  pipe  may  move  in  a  horizontal  or  vertical  direction,  4he  horizontal  move- 
ment being  taken  care  of  by  the  knife-edges,  which  rest  on  roller  bearings,  while  the 
vertical  movement  is  taken  care  of  by  two  counterweights ;  for  ordinary  power  plant 
work  this  system  may  be  easily  simplified. 


192 


STEAM-ELECTRIC  POWER  PLANTS. 


FIG.  ii.      Pipe  Supports,  Anchor  and  Wall  Sleeve. 


HIGH-PRESSURE  PIPING. 


193 


FIG.  12.     Bracket  for  Pipe  Riser. 


FIG.  13.     Balanced  Support  for  Pipe  Riser,  allowing  movement  in 
vertical  and  horizontal  direction. 


STEAM-ELECTRIC  POWER  PLANTS. 


w 

3* 

•  iS"  27  2T  ST  ^T          •*•  •*»       •*•     •*•            **»<*«• 

.£  CD  OJ   CO   O   t^       t-  U5  O  00  OS       OlOOCDrH 

i-i  CXI   N    i-i                                                  rH 

QQ       V 

Its 

C                    N  OS       *i<  IO  O  O  C-      00  O  C9  OS  US 

^ 

^ 

rH    rH    rH   rH 

rH     « 

S.-OT5 

rJTrtr,-t._tr_m       _fn  -"I-  ---»-  -Hi       -t"  -*l          -t»>4- 

rf« 

£OOS^J*O05       t~  i—  1   10   CS   i—  '       rHCOCDOSO 

03  05 

CD   Tf'CO        rH    i-H    IO      u 

_  =03 

-1        or   = 

g-8 

jj                                       N050503Tjl^USCDC»00 

o  exj 

CO  TJ*   CD       CO   00   O     ti, 

e^tCOCOCSCS)       lOOOOMrjl      CDOCDOCO 

03  O 

CDOO       OCOCDOOO 

oe 

2*                                                                           N  05  05  ^  ^ 

US  CO 

rH    rH    rH    rH 

•«>  n-r  <rr  -*•-*•       rH^Nri*          ^!«       *4»                 t*r  e»» 
BCSIOOQO^IO       rHQON0503       OlOOCDrH 
•"  rH   rH   rH                                                                 rH 

CO     v 

K*                      09   OS       05  ^  US.  US  CO       C^  05  rH  0^   ^ 

fc 

CD     u 

M    w 

-to            f| 

c  CD   OS   O  ^   00       OS^OOrH       rHQOCOOSO 

OS  US 

(N    O   CO        rH  rH   US      V 

o 

•l-l  rH       CXI                 rH              rH 

O    -      - 

£                                          CsfCStCSIOSOS^IlOCDC"- 

00  05 

-NNCxTo305      ^5"lO«5CD      CDCDCDCDCO 

CO  O 

O  O  •*      rjlTtlTjlCDCDCO 

< 

exj 

Ol  N  CXI       CXI  CXI  W 

z 

N  N  N 

LJ 

N 

rH  rH  rH*«  N*      OSOS^^US       O  C-  CO  C6  O 

USCOCO      OCXlTJlCOOOO 

W 

to 


3 


t/)      T!    rH 


cS 

H 

J3 

'r« 
t/5 

C 

m 

"-i-i 
o 


"*• 

M 

6 


HIGH-PRESSURE  PIPING. 


195 


Fittings.  —  In  order  to  decrease  the  cost  of  piping  as  well  as  to  minimize  the  liability 
of  leakage,  the  number  of  fittings  should  be  reduced  as  much  as  possible.     Modern 


FIG.  i4a.      Harters  Expansion  Joint. 

practice    is  to  use  welded  or  seamless  drawn  steel  pipe.     These  pipes  are  usually 
obtained  in  America  in  lengths  up  to  20  to  21  feet,  while  in  Europe,  and  especially  on 


FIG.  i4b.     Slip  Joint. 

the  Continent,  pipes  in  lengths  up  to  50  feet  are  easily  obtainable.  The  benefit  of 
using  long  lengths  consists  in  the  reduced  cost  of  piping  due  to  the  fewer  joints,  which 
at  the  same  time  reduce  the  liability  of  leakage. 


196 


STEAM-ELECTRIC   POWER   PLANTS. 


Wherever  possible  cast  elbows  should  be  avoided  and  pipe  bends  similar  to  those 
illustrated  in  Fig.  14  employed.  The  radius  of  these  bends  must  be  at  least  five  to  six 
times  the  diameter  of  the  pipe,  while  in  exceptional  cases  four  times  the  diameter  may 
be  taken.  This  latter,  however,  is  not  favored,  owing  to  the  difficulty  in  manufacturing 
same.  A  straight  length  of  pipe  should  be  left  on  the  end  of  the  bend,  as  indicated  by 
"A"  in  Fig.  14,  which  varies  in  different  size  pipe  and  different  manufactures.  For 
instance,  a  14-inch  pipe  may  need  20  inches  of  straight  length,  while  a  6-inch  pipe  needs 
6  inches  straight  length,  according  to  attached  table,  which  is  from  the  Pittsburg  Valve, 
Foundry  and  Construction  Company. 


SADDLE   NOZZLE 


EXTENSION    ELBOW  WITH   BASE 


OFFSET 


DOUBLE  OUTLET  TEE 


RETURN    BEND 


FIG.  15.     Cast  Fittings. 

Where  space  and  conditions  do  not  allow  of  using  long  radius  bends,  cast  fittings 
must  be  employed.  These  should  be  made  of  first-class  cast-iron,  steel  or  semi-steel; 
such  fittings  are  illustrated  in  Figs.  15  and  16;  the  latter  is  accompanied  by  a  table, 
giving  the  main  dimensions  for  fittings  suitable  for  250  pounds  working  pressure  and 
are  of  the  Crane  Company's  make.  These  dimensions  vary  slightly,  according  to 


HIGH-PRESSURE  PIPING. 


197 


i 


-A— > 


1 


f 


Size  of  Run  ....... 

Inches. 

2 

24 

3 

34 

4 

44 

5 

6 

7 

8 

9 

Outlets  

ALL  REDUCING  FITTINGS  2"  TO  9"  INCLUSIVE  AKE  THE  SAME  DIMENSIONS 
AS  STRAIGHT  FITTINGS  CENTER  TO  FACE. 

Face  to  face  

AA 

10 

11 

12 

13 

14 

15 

16 

17 

18 

20 

21 

Cent,  to  face  

A 

5 

54 

6 

6| 

7 

74 

8 

84 

9 

10 

104 

Cent,  to  Face  of  45°  Ells.  .  . 

C 

3 

34 

34 

4 

44 

44 

5 

54 

6 

6 

64 

Cent  to  base  of  base  Ells.  . 

B 

5 

6 

6i 

6f 

7 

7± 

74 

8 

81 

9* 

10 

Diameter  of  Flanges  

Inches. 

64 

74 

8i 

9 

10 

104 

11 

124 

14 

15 

16 

Thickness  of  Flanges  

Inches. 

£ 

1 

a 

1A 

u 

1A 

If 

1* 

14 

If 

11 

Size  of  Run  

Inches. 

10 

12 

14 

15 

16 

18 

20 

22 

24 

Outlets  

7  and 
Larger 

9  and 
Larger 

10  and 
Larger 

10  and 
Larger 

12  and 
Larger 

14  and 
Larger 

16  and 
Larger 

16  and 
Larger 

16  and 
Larger 

Face  to  face  

AA 

23 

26 

29 

.30 

32 

34 

37 

40 

44 

Cent,  to  face  

A 

ru 

13 

144 

15 

16 

17 

184 

20 

22 

Cent  to  face  of  45°  Ells.  .  . 

C 

7 

8 

8 

84 

9 

94 

10 

104 

114 

Cent,  to  base  of  base  Ells  .  . 

B 

104 

11 

14 

144 

15* 

154 

16| 

17f 

18* 

Diameter  of  Flanges  .  .  .  •.  . 

Inches. 

174 

20 

22| 

234 

25 

27 

294 

314 

34 

Thickness  of  Flanges  . 

Inches. 

i* 

2 

n 

2& 

2± 

2f 

24 

2f 

21 

TEES    INCREASING    ON    THE    OUTLET 

Tees  having  outlet  larger  than  the  run  will  be  the  same  length  center  to  face 
of  all  openings  as  a  Tee  with  all  openings  of  the  size  of  the  outlet. 

EXAMPLE 

A 12"  x  12"  x  18"  Tee  will  be  governed  by  the  dimensions  of  the  18-inch  Tee. 
namely,  17  inches  center  to  face.. of  all  openings,  and  34  inches  face  to  face. 
The  face  to  face  dimensions  of  Flanged  Fittings  are  not  changed  by  a  reduction 
on  the  run. 

FIG.  1 6.     Fittings  Suitable  for  250  Ibs.  Working  Pressure  (Crane  Co). 


198 


STEAM-ELECTRIC   POWER   PLANTS. 


different  manufacturers.     Some  engineers  condemn  cast  iron  altogether  for  any  part 
of  a  modern  pipe  line. 

For  a  number  of  years  cast  fittings  have  been  done  away  with  in  Europe  to  a  great 
extent  and  have  been  replaced  by  welded  fittings;  a  good  example  of  this  practice  is 
the  piping  system  of  the  new  Summer  Lane  plant,  Birmingham,  England. 


FIG.  17.     Welded  Steel  Fittings  with  loose  flanges. 


Fig.  17  represents  such  fittings  made  up  entirely  of  wrought  iron  or  steel;  as  will 
be  noticed  in  the  illustration,  these  fittings  are  provided  with  loose  movable  flanges. 
Practically  any  desired  form  or  size  may  be  obtained,  an  example  of  which  is  given  in 
Fig.  1 8,  which  represents  a  manifold.  These  fittings  are,  of  course,  more  expensive 
than  common  cast-iron  ones;  the  process  of  making  them  is  not  a  secret,  and  a  number 
of  manufacturers,  especially  abroad,  turn  them  out  under  various  processes.  The 


HIGH-PRESSURE  PIPING. 


199 


author  is  of  the  opinion  that  within  some  years  these  fittings  will  be  generally  found  in 
power-house  practice,  as  their  many  advantages  are  obvious. 


FIG.  1 8.     Welded  Manifold  with  Loose  Flanges. 

In  calculating  the  thickness  of  the  walls  of  pipes  or  fittings,  a  factor  of  safety  of 
from  five  to  eight  should  be  allowed. 

The  tensile  strength  of  good  pipe  material  averages  as  follows: 


MATERIAL. 

TENSILE  STRENGTH 
IN  POUNDS 
PER  SQUARE  INCH. 

Cast  Iron      

15,000 

Copper          .             .                 ... 

20.000 

Wrought  Iron      

^o.ooo 

Mild  Steel    

60,000 

A  formula  for  calculating  thickness  of  pipe  shell  is  as  follows: 

pds 


in  which 


t  = 
i 

t  =  Thickness  of  pipe  shell  in  inches. 
p  =  Pressure  in  pounds  per  square  inch. 
d  =  Internal  diameter  in  inches. 
T  =  Tensile  strength. 
S  =  Factor  of  safety. 


Where  globe  valves  are  employed,  twice  the  above  lengths  should  be  added  for  each 
valve.  Where  other  fittings,  such  as  long  sweep  ells,  manifolds,  etc.  are  used,  the 
designer  must  use  his  own  judgment. 

Flanges.  — The  most  important  part  of  a  fitting  is  the  flange,  as  it  is  upon  this  that 
the  principal  cost  of  maintenance  depends.  Although  each  manufacturer  may  have  a 
specially  designed  flange,  there  is  in  America  a  standard  flange,  which  was  agreed  upon 
by  the  leading  manufacturers  at  a  meeting  held  June  28,  1901;  this  is  known  as  the 
Manufacturers'  Standard  (see  Fig.  19).  Many  power  plant  designers,  however,  have 
their  own  flange,  one  of  which  is  given  in  Fig.  20,  and  was  originally  designed  for  the 


2OO 


STEAM-ELECTRIC  POWER  PLANTS. 


59th  Street  station  in  New  York,  and  has  since  been  used  in  several  other  plants. 
It  will  be  noticed  that  these  fittings  are  of  unusual  strength;  the  left-hand  illustration 


* 

&IX.C. 

r 

B..,,.  ,  .     3 

A 

rl 

SIZE 

A 

B 

No.  Holes 

D 

Size  Bolt 

Length  of 
Bolt 

1 

4} 

31 

4 

| 

1 

2 

11 

5 
6 

3| 

4} 

4 
4 

i 
$ 

| 

21 

2} 

2 

6} 

5 

4 

| 

2} 

2} 

7} 

51 

4 

1 

i 

3 

81 

f 

}| 

8 

ij 

i 

2J 

3} 

9 

71 

8 

ij 

I 

2i 

4 

10 

7| 

8 

| 

i 

3 

4} 

10} 

E 

t« 

8 

I 

! 

31 

5 

11 

I 

n 

8 

I 

'  • 

31 

6 

12} 

1C 

>i 

12 

i 

I 

3} 

7 

14 

m 

12 

1 

i 

3* 

8 

15 

13 

12 

1 

I 

3? 

e 

16 

14 

12 

1 

i 

4 

10 

17} 

151 

16 

1 

I 

4 

12 

20 

17J 

16 

1 

I 

41 

14 

22$ 

20 

20 

1 

I 

4} 

15 

23} 

21 

20 

li 

1 

4* 

16 

25 

22.', 

2O 

H 

1 

6 

18 

27 

24} 

24 

li 

1 

61 

20 

29J 

263 

24 

H 

li 

5* 

22 

31} 

28:,' 

28 

11 

li 

5* 

24 

34" 

311 

28 

11 

14 

6 

26 

361 

33} 

32 

li 

61 

28 

38} 

35  i 

32 

11 

li 

6} 

NOTE.— Flanges,  Flanged  Fitting^  Valves;- etc.,  are  drilled  in  multiples  of 
four,  so  that  fittings  may  be  made  to  face  in  any  quarter  and  holes  straddle 
center-line. 

FIG.  19.     Standard  Flange  Drilling  for  175  Ibs.  Working  Pressure,  adopted  by  the  leading 
manufacturers  of  America,  June  28,  1901. 


in  Fig.  20  represents  a  cast-iron  or  semi-steel  flange,  while  the  right-hand  is  of  the  loose 
flange  type.     This  flange  is  usually,  but  erroneously,  called  in  America  the  Van  Stone 


HIGH-PRESSURE  PIPING. 


2OI 


Is 


i-l     I    i-l    I    O5        CO 


CO        i-l        i-l 


'*•?'   I  I   "S?   I    ^   I   ^       "*-S° 

•o   I  -^    I   ^f\   I   ^rx       rtv 

n    |   CO     |    rl  1  i-(    I   CO        CO 


Q    W 


if? 


O>       CO     I    -H 


t-     I    TH     I    rt 


it 


Le 


•a 

o 

!* 

<u 


ON 

U 

"*3 

^ 
T3 

O 

a! 

en 
cj 


PH 


202 


STEAM-ELECTRIC   POWER   PLANTS. 


joint.     Attention  is  called  to  the  fact  that  in  flaring  the  end  of  the  pipe  the  flared  end 
becomes  thinner  than  the  pipe  shell  itself,  especially  after  being  faced;  this  will  result 


IT   * 


***  -*-  Nf  NT 

—      X  (J^    — N 


M 


S* 


!r 


^x 


^  * 


^^^^^ 


>??^ 


*^ 


^>?^^ 


QN 


jqSj? 


» -A1  £k2 


*** 


X 


?s»* 


i*;**^^ 


S 


PH 
O 


tUD 


in  an  improper  joint.  To  overcome  this  the  loose  flange  abutting  against  the  flared 
end  should  be  slightly  sloped,  in  order  to  give  an  even  contact  to  the  entire  surface. 
A  still  better  method  is  to  reinforce  or  upset  the  pipe  end  before  it  is  flared  over.  A 


HIGH-PRESSURE  PIPING. 


203 


flange  which  complies  with  the  above-mentioned  condition  is  shown  in  Fig.  21 ;  in  this 
case  a  reinforcing  ring  is  welded  on  the  pipe,  while  a  loose  flange  is  so  arranged  that  it 


Cast  or  Forced  Steel  Welded  Iron 


Copper 


FIG.  22.     Standard  Flanges  of  the  Verein  deutscher  Ingenieure. 

shoulders  on  the  above-mentioned  ring  on  a  forty-five  degree  bevel.  This  type  of  flange 
has  been  adopted  for  a  pressure  of  20  atmospheres  (294  pounds)  by  the  "Verein  deutcher 
Ingenieure"  in  1900.  The  accompanying  table,  Fig  21,  is  the  standard  adopted  and 


204 


STEAM-ELECTRIC   POWER   PLANTS. 


Cast  or  Forged  Steel  Welded  Iron 


Copper 


Bronze 


FIG.  23.     Standard  Flanges  of  the  Verein  deutscher  Ingenieure. 


HIGH-PRESSURE  PIPING. 


205 


has  been  converted  by  the  author  from  the  metric  system  to  read  in  inches  and  the 
fractional  parts  of  an  inch.  All  dimensions  have  been  slightly  increased  over  what 
the  converted  figure  would  be ;  number  and  size  of  bolt  have  not  been  changed. 


Valve  without  by-pass. 


Valves  below  8"  are  made  without  Ribs. 
Valves  8"  and  above  are  ribbed. 


3    ,4 


85410 


15V416Mtl8^ 
18'B20\J22H 


12 


«       7      8      10     12     14    15     16    18    20    22    24    28 


3" 
19 


154 


42 
15 

IX 


15 

IT-* 

20 
33'437 


47 
18 

2% 
16 

i^ 


ifflJL      ai 

%26 


-,, 
>4j23-' 

49 


42 

54     63' 

18     21 

$ 
17 

l«L 


22 


26 


1954  20%  22 


29 


27 

2% 


34 

2% 


33X35:437%40 

69    |74     82\~- 
89^,96^107  % 


254 
5 

25^26 
3 


it 


47 


117 


153  216 


"N"  size  of  by-pass.     "O"  No.  turns  to  open. 

The  bore  of  all  gates  14  inches  and  larger  is  made  to  suit  the  inside  dimension! 
of  O.  D.  pipe.    For  standard  flange  dimensions  see  ' 

FIG.  24.     Taper  Seat  Gate  Valve,  250  Ibs.  working  pressure, 
(Pittsburg  Valve,  F.  and  C.  Co). 

A  number  of  flanges  that  have  been  adopted  by  the  above-mentioned  society  is 
given  in  Figs.  22  and  23.  From  these  designs  a  type  to  suit  any  condition  may  be 
selected,  since  they  are  suitable  for  high  and  low  pressure,  both  for  steam  and  water 


2O6 


STEAM-ELECTRIC   POWER   PLANTS. 


pipes.  All  joints  are  provided  with  loose  flanges  similar  to  the  table  given  in  Fig.  21. 
One  benefit  of  these  loose  flanges  is  the  greater  variety  of  angles  which  may  be  obtained, 
for  the  bolt  holes  always  match. 

The  pipe  flanges,  according  to  good  practice,  should  be  provided  with  a  number  of 
bolt  holes  which  is  a  multiple  of  four,  in  order  to  shift  cast  fittings,  should  it  be  required, 
90°;  some  multiples  of  four  may  be  shifted  45°  and  still  match  the  bolt  holes.  Some 
power  plant  designers  claim  this  practice  to  be  indispensable,  but  the  author  does  not 
agree  with  them,  although  it  may  be  a  good  practice.  All  pipes  above  3  inches  diameter 
should  be  flanged,  while  below  3  inches  screwed  fittings  may  be  used. 


FIG.  25.   Superheated  Steam  Valve  with 
By-pass. 


FIG.  26.  High-Pressure  Superheated 
Steam  Globe  Valve. 


To  a  great  extent  in  American  practice  ground  joints  are  used  which,  when  properly 
made,  are  undoubtedly  superior  to  any  other,  while  in  Europe  gaskets  are  used  almost 
exclusively.  In  using  ground  joints  a  straight  face  is  preferable,  while  in  employing 
gaskets  either  straight  face,  male  and  female  or  tongue  and  groove  joints  may  be  used. 
Gaskets  may  be  made  of  corrugated  copper  rings,  an  improved  type  of  which  is  one 
which  has  asbestos  rings  placed  in  the  corrugation.  Corrugated  gaskets  may  also  be 
made  of  soft  steel.  Another  gasket  is  made  up  of  copper  wire  cloth  or  ring;  the  latter 
gaskets  are  especially  adapted  to  a  tongue  and  grooved  joint. 

Valves.  —  The  valves  employed  for  the  main  steam  pipes  are  of  two  types,  either 
globe  or  gate  valve.  American  and  English  practices  favor  gate  valves,  while  on  the 
Continent  globe  valves  are  used  exclusively.  This  is  due  to  the  fact  that  the  former 


HIGH-PRESSURE  PIPING. 


207 


are  cheaper,  while  the  latter  are  more  suitable  for  a  high  degree  of  superheated  steam. 
When  specifying  valves  for  superheated  steam,  care  should  be  taken  that  no  soft  com- 
position is  used.  For  instance,  in  a  globe  valve  the  disc  and  seat  should  be  made  of 
a  hard  alloy,  such  as  gun  metal,  nickel  steel,  etc.;  also  the  stuffing-box  gland,  so  far 
as  it  will  come  in  contact  with  the  steam,  should  be  made  of  the  same  material;  the 


SIZE. 

A 

6 

6 

7 

8 

10 

A 

10 

11 

12J, 

14 

15 

17* 

D 

li 

U 

i* 

U 

If 

H 

E 

12 

13* 

17 

20 

21 

25 

F 

6 

6| 

8} 

10 

1OJ 

12J 

H 

17| 

21J 

22f 

251 

27i 

32} 

1 

9 

12 

15 

15 

18 

21 

K 

u 

li 

U 

H 

11 

2 

FIG.  27.     Non-Return  Valve  for  250  Ibs.  Working  Pressure  (Pittsburg  Valve,  F.  &  C.  Co.) 

same  may  be  said  in  specifying  a  gate  valve  so  far  as  pertains  to  the  seat,  gate  and  gland. 
Fig.  24  represents  a  well-designed  gate  valve,  as  manufactured  by  the  Pittsburg  Valve, 
Foundry  and  Construction  Company,  while  Figs.  25  and  26  show  typical  continental 
globe  valves.  In  the  latter  the  seat  and  body  are  made  of  one  piece,  while  the  disc 
itself  is  made  of  the  same  metal  as  the  body,  namely,  cast  iron.  It  will  be  noticed 
that  the  disc  is  drilled  for  a  by-pass  valve  operated  by  the  main  spindle;  by-pass 
is  used  both  for  globe  and  gate  valves  of  sizes  above  8  inches  or  10  inches. 


208 


STEAM-ELECTRIC   POWER   PLANTS. 


In  using  globe  valves  they  should  be  so  placed  that  the  pressure  is  under  the  disc. 
Attention  is  called  to  Fig.  25,  in  which  an  arrow  indicates  steam  entering  on  the  top  of 
disc;  the  disadvantage  of  this  design  is  that  to  pack  a  valve  the  entire  line  must  be 
shut  down,  or  if  the  spindle  should  break  the  disc  will  fall  on  the  seat  and  act  as  a 
check  valve.  A  globe  valve  should  never  be  placed  in  a  vertical  position  in  a  steam 

line,  unless  proper  provision  be  made  for  drips,  but 
should  be  installed  at  a  slight  angle  off  the  horizontal 
(enough  to  keep  the  stuffing  box  dry)  so  that  a  free 
and  unobstructed  passage  is  left  for  the  flow  of  water 
of  condensation.  No  steam  valves  should  be  placed 
with  the  stem  looking  down,  so  that  there  will  be  no 
place  for  the  collection  of  water  around  the  stuffing 
box. 

All  valves  should  be  so  placed  as  to  be  readily 
accessible,  either  from  the  floor  or  from  a  gallery. 
Frequently  this  feature  is  overlooked  and  ladders 
have  to  be  used,  which  seriously  hampers  the  suc- 
cessful operation  of  the  plant.  Wherever  it  is  impos- 
sible to  so  place  the  valves,  bevel  gearing  and  rod  or 
an  endless  chain  may  be  used. 

Besides  those  described  above,  there  are  a  num- 
ber of  other  valves,  such  as  automatic  stop  valves, 


FIG.  28. 
Automatic  Closing  Valve. 


FIG.  29.  Automatic  Closing  Valve  (System 
Schaffer  and  Budenburg),  acts  in  both  direc- 
tions of  flow  of  steam. 


pressure-reducing  valves,  etc.,  which  come  into  consideration  in  designing  the  main 
steam  piping.  In  the  steam  connection,  between  the  boiler  and  the  boiler  header, 
and  directly  on  the  boiler  nozzle,  a  non-return  valve  should  be  placed,  so  that  in 
case  of  any  serious  falls  in  pressure  in  a  particular  boiler  no  steam  from  the  header 
can  return  to  the  boiler,  the  valve  opening  automatically  when  the  affected  boiler  again 
regains  its  normal  pressure.  A  valve  of  this  character  is  shown  in  Fig.  27 ;  this  valve 


HIGH-PRESSURE  PIPING. 


209 


will  operate  in  one  direction  only,  while  a  valve  closing  in  both  directions  of  the  flow 
of  steam,  so  that  in  case  of  a  fracture  either  in  the  main  steam  line  or  in  the  boiler 
itself,  the  increased  velocity  of  the  steam  would  close  the  valve,  as  seen  in  Fig.  29. 
Provision  is  made  to  regulate  for  the  required  velocity;  another  automatic  closing 
valve,  built  either  for  angle  or  straight,  for  vertical  or  horizontal  position,  is  given  in 
Fig.  28.  It  is  the  Hubner  &  Mayer  patent  of  Vienna  and  is  on  the  market  both  in 
England  and  America. 

In  large  power  plants  it  might  be  admissible  to  operate  the  main  valves  from  one 
central  point.  This  may  serve  especially  in  case  of  an  accident.  The  valves  may  be 
operated  either  by  electric  motors,  air,  steam  or  water  pressure. 

In  many  power  plants  where  the  auxiliaries  are  steam  driven,  reducing  valves  are 
placed  in  the  steam  line  to  reduce  from  a  high  pressure  to  a  lower  one  suitable  for  the 


FIG.  30.    Anderson  Reducing  Valve. 


FIG.  31.     Stratton  Separator. 


machinery  (Fig.  30).  The  reason  for  this  reduction  in  pressure  is  that  many  manu- 
facturers have  not  designed  auxiliaries  suitable  for  the  high  pressure  used  in  the  main 
engines.  However,  "modern"  auxiliaries  are  being  designed  for  high  pressure,  thus 


210 


STEAM-ELECTRIC   POWER   PLANTS. 


doing  away  with  the  necessity  of  employing  a  reducing  valve  and  separate  pipe  line, 
and  increasing  the  convenience  of  operation. 

Most  high-pressure  reducing  valves  are  of  the  spring  type  and  are  adjusted  by  means 
of  a  set  screw,  which  increases  or  decreases  the  tension  of  the  spring.  It  is  natural 
that  a  spring  under  a  constant  stress  should  weaken,  thereby  changing  the  pressure 
at  the  delivery  side  of  the  valve;  this  must  be  attended  to  during  operation.  In  select- 
ing a  reducing  valve,  one  should  be  decided  upon  that  has  few  parts  and  is  simple  in 
design;  there  are  a  number  of  these  on  the  market. 

Drip  System.  —  The  drip  system  in  a  saturated  steam  plant  is  more  important 
than  when  superheated  steam  is  used,  since  superheated  steam,  especially  with  a  high 
degree  of  temperature,  contains  little  or  no  water,  while  with  saturated  steam  a  con- 
siderable amount  of  water  is  carried  from  the  boiler,  and  makes  it  necessary  to  employ 
separators,  or  so-called  "water  catchers."  These  water  catchers  are  designed  for 
the  purpose  of  removing  water  from  the  steam.  Some  designs  are  shown  in  the 


FIG.  32.     Cochrane  Horizontal  Separators. 

accompanying  illustration.  Other  types  are  of  a  combined  system,  acting  as  a  water 
catcher  and  steam  collector;  these  are  large  bodies,  usually  made  of  wrought  iron 
or  steel  plates  and  are  used  exclusively  in  plants  in  which  reciprocating  engines  are 
installed.  This  apparatus  should  be  large  enough  to  hold  enough  steam  to  reduce 
the  vibration  of  the  pipes,  which  is  caused  by  the  sudden  cut-off  in  the  valve  motion; 
such  steam  reservoirs  should  be  employed  both  for  saturated  and  superheated  steam. 
The  steady  flow  of  steam  to  a  turbine  eliminates  the  necessity  for  these  reservoirs. 

Where  superheated  steam  is  used  the  pipe  lines  should  be  provided  with  a  drip 
system.  It  is  claimed  frequently  in  using  superheated  steam  that  no  drip  system 
need  be  employed.  This  is  an  error,  as  there  is  no  superheated  steam  conveyed  but 
what  there  may  be  more  or  less  condensation  in  the  pipe.  There  should  be,  at  least, 
one  drip  provided  directly  before  the  steam  enters  the  prime  mover.  This  may  be 


HIGH-PRESSURE  PIPING. 


211 


accomplished   by  inserting  a  tee  in   the  line  with  the  outlet  looking  downward,  thus 

forming  a  pocket  from  which  a  small  drip  pipe  is  connected. 

High-pressure  drip  connections  should  be  run  through  traps  to  a  receiving  tank 

or  heater  from  which  the  water  may  be  fed  to  the  boiler.     As  all  traps  are  troublesome 

and  sooner  or  later  get  "out  of  commission, 
it  is  necessary  to  by-pass  same  to  make 
repairs  conveniently.  The  main  steam- 
pipe  line  and  valves  have  also  to  be  provided 
with  a  bleeder  system,  so  that  before  turn- 
ing steam  upon  a  cold  pipe  the  water  in  the 
line  may  be  drawn  off.  As  a  number  of  drips 
are  connected  to  one  trap,  this  bleeder  line 


INLET 


OUTLET 


FIG.  33.    Thoen  Steam  Trap. 


FIG.  34.    Columbia  Expansion  Trap. 


should  run  directly  to  a  tank  or  some  other  system  of  water  disposal.  Special  attention 
is  called  to  the  above,  since  frequently  the  mistake  is  made  of  connecting  this  low- 
pressure  bleeder  system  to  the  high-pressure  drip,  the  result  of  which  is  that  the  high- 
pressure  drip  will  back  up  into  the  main  steam  piping.  In  fact,  the  design  of  an  efficient 

drip  system  is  one  of  the  most 
difficult  problems.  Many  power 
plant  designers  are  of  the  opinion 
that  such  small  piping  should  not 
be  put  on  paper,  but  should  be 
left  to  the  erecter.  This  might 
be  well  for  power  plants  in 
which  the  increased  consump- 
tion of  water  and  coal,  due  to 
FIG.  35.  Mark  Trap,  Connected.  improper  draining,  is  not  a 

factor.  The  author  has  experi- 
enced, in  some  cases,  more  difficulty  with  the  drip  system  than  with  the  main 
steam  piping. 

There  are  drip  systems  in  practical  use  which  return  the  water  of  condensation 
directly  to  the  boiler.  These  systems,  however,  require  special  provisions ;  for  instance, 
the  Holly  gravity  return  system,  which  operates  as  follows:  The  drip  pipes  from 
the  various  points  are  led  to  a  receiver,  which  is  placed  at  a  point  below  the  lowest 


212 


STEAM-ELECTRIC   POWER   PLANTS. 


drainage  outlet,  usually  about  the  central  point  of  the  plant.  A  riser  pipe  from  the 
receiver  reaches  to  the  discharge  chamber  thirty  feet  or  more  above  the  boiler  water 
line,  and  a  return  pipe  connects  the  discharge  chamber  to  the  boiler  at  some  point  below 
the  water  line.  The  water  of  condensation  is  carried  by  the  movement  of  steam  to 


FIG.  36.    Cookson  Trap,  Connected. 

the  discharge  chamber  by  entrainment,  and  care  is  taken  that  the  altitude  of  the  dis- 
charge chamber  is  great  enough  to  permit  of  the  accumulation  of  sufficient  head  in 
the  return  line  to  restore  the  pressure  loss  under  all  conditions,  and  to  make  the 
return  to  the  boiler.  The  system  is  kept  free  from  air  and  the  riser  action  is  accel- 

TABLE    II. —  EXPERIMENTS   ON   THE   LOSS   OF   HEAT   FROM   BARE   STEAM   PIPES. 


& 

£ 

§ 

5 

CU 

-  • 

4>   O 

£  . 

8. 

"8  u 

I 

05 

o 
£  . 

0 
V 

H   . 

U* 

c/)  <D 

|a 

•xU 

0, 

v« 

36 

O   u 

?  i-  3 

NAME  OF  EXPERIMENTER. 

"8 

w 

IP 

S.3 

Is 

>-  o 

|l 

j 

• 

1 

1 

ctco 

i 

"8121 

&* 

M<   pj 

3 

a 

LH 

H 

^ 

rs  S 

f™1      21 

*" 

55 

c/2 

£ 

Q 

j^3 

CO 

Barrus      

?.? 

7 

2" 

63.57 

82.2 

325.2 

56.6 

268.6 

•9IS 

3.01 

Barrus      

4-3 

7 

2" 

63.92 

149.6 

365-4 

63.2 

302.2 

1.150 

3-25 

Barrus      

2.7 

3 

10" 

98-33 

149.3 

365.3 

73-6 

291.7 

1.085 

3.18 

Hudson-Beare     

i 

3-53* 

8.13 

135.0 

67.0 

291.0 

1.050 

3.10 

130  pounds      

48 

i 

2" 

50.66 

128.7 

354-7 

80.1 

274.6 

•994 

3-13 

i 

2" 

7.63 

53-4 

300.8 

71.2 

229.6 

.707 

2.78 

Brill                       

i 

4 

8" 

135-4 

110.5 

344-5 

75-5 

269.0 

•834 

2.71 

*  Actual  outside  diameter. 


HIGH-PRESSURE  PIPING.  213 

crated  by  the  venting  of  a  small  amount  of  vapor  from  the  discharge  chamber,  this 
being  usually  discharged  into  the  feed- water  heater. 

Pipe  Covering.  —  What  the  condensation  in  bare  pipes  amounts  to  is  fully  treated 
by  Paulding  in  "  Steam  in  Covered  and  Bare  Pipes."  Table  II,  computed  by  the  above 
author  (see  page  212)  showing  the  results  obtained  by  various  experimenters  with 
different  sizes  of  pipes  and  different  pressures.  For  ordinary  calculation  an  average 
of  three  B.  T.  U.  per  hour  per  square  foot  of  exposed  surface  may  be  assumed. 

To  calculate  the  financial  loss  due  to  using  a  bare  pipe  over  that  of  a  covered  one, 
the  following  formulas  may  be  used,  assuming  a  short  ton  (2,000  pounds);  if  a  long 
ton  is  used  the  constant  is  2,240  pounds. 

3  A  (t  -  0  N  X  C 

Cost  per  annum  of  steam  condensed  =   — 7 — 5-3 —      — F~ 

905.8  X  2,000  h, 

in  which 

A  =  Area  of  exposed  pipe  surface  in  square  feet. 
/  =  Temperature  Fahr.  of  steam. 

tl  =  Average  temperature  Fahr.  of  surrounding  water. 
N  =  Hours  per  annum  steam  is  in  the  pipe  line. 
E  =  Evaporation  from  and  at  212°  Fahr.  per  Ib.  of  coal. 
C  =  Cost  of  coal  and  handling,  per  ton. 

By  using  this  formula  the  percentage  saved  by  the  covering  is  ascertained. 

In  order  to  reduce  the  condensation  in  the  pipe,  it  is  necessary  to  give  same  a  proper 
insulating  covering.  Pipe  coverings  are  valued  by  the  percentage  of  saving  in  con- 
densation over  that  which  occurs  in  a  bare  pipe;  they  range  from  65  per  cent  to  85  per 
cent  and  higher.  There  are  many  varieties  on  the  market;  the  material  used  ranges 
from  an  earthy  substance  up  to  silk. 

All  pipe  covering  should  be  non-combustible;  some  of  the  materials  used  in  cover- 
ing are  as  follows :  hair  felt,  magnesia,  asbestos,  silk,  Kieselguhr  and  similar  earthy  sub- 
stances. The  covering  frequently  used  in  American  practice  consists  of  85  per  cent 
carbonate  of  magnesia  mixed  with  15  per  cent  of  asbestos.  This  covering  is  applied  to 
the  pipe  in  molded  sections  and  usually  in  two  layers,  the  seams  of  which  are  staggered 
and  filled  with  magnesia  plaster.  The  thickness  of  these  coverings  depends  on  the 
size  of  pipe,  although  the  radiation  per  square  foot  of  surface  is  the  same  in  a  small 
as  in  a  large  pipe.  The  practice,  however,  is,  in  a  first-class  covering,  to  employ 
2-inch  covering  up  to  2-inch  pipe,  2|-inch  up  to  8-inch,  and  3-inch  on  any  size 
above.  The  sections  are  bound  to  the  pipe  by  means  of  galvanized  iron  wire  or 
netting,  over  which  is  wrapped  a  coat  of  rosin-sized  paper  followed  by  eight-ounce 
canvas  securely  sewed  on. 

There  are  in  England  and  America  other  efficient  systems  of  pipe  covering  in  use; 
for  instance,  the  asbestos  air-cell  covering,  which  consists  of  several  layers  of  corru- 
gated asbestos  sheets,  making  a  laminated  covering  in  which  the  corrugations  form  an 
air  space. 

>      of    -rut 

UNIVERSITY 


214  STEAM-ELECTRIC  POWER  PLANTS. 

On  the  Continent  of  Europe,  Kieselguhr  is  used  to  a  great  extent.  It  is  a  pulverized 
earthy  substance,  and  before  it  is  applied  to  the  pipes  it  is  made  into  a  paste  and  is  then 
plastered  in  several  courses  on  the  pipes  and  sewed  in  with  canvas.  With  this  cover- 
ing when  organic  bodies  are  mixed  with  the  paste,  and  after  steam  is  turned  into  the 
pipes,  these  organic  particles  shrink,  leaving  numerous  small  air  spaces  and  increasing 
the  efficiency  of  the  covering.  Another  plan  is  to  wrap  either  the  plain  Kieselguhr,  or 
the  Kieselguhr  with  organic  particles,  in  raw  silk. 

Another  efficient  covering  is  one  in  which  an  air  space  is  employed.  A  system  of 
this  kind  is  the  Pasquay.  The  covering  consists  of  perforated  iron  furred  out  from 
the  pipe,  over  which  raw  silk  is  wrapped,  and  a  second  jacket  in  a  similar  way  is  placed 
upon  the  first  one.  The  efficiency  of  this  and  the  Kieselguhr  covering  exceeds  85  per 
cent. 

In  a  paper  by  Mr.  H.  G.  Stott,  entitled  "Steam  Pipe  Covering  and  its  Relation  to 
Station  Economy,"  read  before  the  Association  of  Edison  Illuminating  Companies  in 
1902,  this  subject  was  very  thoroughly  covered  by  Mr.  Stott,  who  conducted  tests  to 
determine  the  most  efficient  type  and  thickness  of  covering,  before  awarding  the  con- 
tract for  the  Manhattan  Elevated  Railroad  station. 

The  method  adopted  consisted  in  coupling  up  about  200  feet  of  two- inch  iron  pipe 
and  mounting  same  on  wooden  horses  about  three  and  one-half  feet  from  the  floor,  the 
three  lines  of  pipe  being  approximately  four  feet  apart  and  four  feet  from  the  nearest 
wall,  in  order  to  avoid  any  errors  due  to  heat  convection  and  radiation.  Sections 
15  feet  in  length  were  marked  off  on  the  straight  portions  of  the  pipe,  and  so 
arranged  as  not  to  include  any  pipe  couplings  or  bends ;  two  feet  from  each  end  of  each 
section  heavy  potential  wires  were  soldered  on  to  the  pipe,  and  at  the  extreme  ends  of 
the  pipe  1,500,000  cm.  copper  insulated  cables  were  soldered  on,  the  openings  in  the 
pipe  having  been  previously  closed  by  means  of  a  standard  coupling  and  plug.  One 
of  these  cables  ran  direct  to  one  terminal  of  a  250-KW.  2 50- volt  steam-driven,  direct- 
coupled  exciter,  which  was  solely  devoted  to  furnishing  current  for  the  test,  and  had  its 
voltage  variable  within  wide  limits,  so  as  to  furnish  any  current  up  to  1,500  amperes. 
The  cable  connected  to  the  other  end  of  the  pipe  was  then  connected  to  three  ammeter 
shunts  in  series,  in  order  to  enable  the  readings  to  be  easily  checked,  after  which  it  was 
carried  through  a  circuit  breaker  and  switch  to  the  other  exciter  terminal.  The  pipe 
covering  test  was  carried  on  in  a  vault  in  which  there  was  no  source  of  heat  and  no 
possibility  of  drafts  of  air,  and  arranged  so  that  the  section  in  which  the  test  was 
being  carried  on  could  be  locked  up  in  order  to  prevent  interference. 

Altogether  twenty-one  tests  were  made  of  various  constructions  of  coverings. 
The  table  on  following  page,  arranged  in  order  of  efficiency,  shows  the  best  results 
obtained : 

Frequently  the  pipe  covering  after  being  canvas  jacketed  is  painted.  This  paint 
should  be  fireproof  and  of  light  color,  as  light  colors  are  not  heat  absorbents  and  will 
thereby  reduce  radiation.  It  is  a  good  scheme  to  paint  pipes  for  different  purposes  of 
various  colors,  so  that  they  may  be  readily  known,  thereby  enhancing  the  convenience 
of  operation. 


HIGH-PRESSURE  PIPING. 


215 


TABLE  III. 


COVERING. 

B.T.U.  loss  per 
sq.  ft.  at  160  Ibs. 
Pressure  . 

Per  cent.    Heat 
saved  by 
Covering  . 

"Remanit"  (carbonized  silk)  wrapped  

I.7o8 

86.0 

85  per  cent  Magnesia,  sectional  

2.O6O 

84.2 

Solid  Cork,  sectional      

2.  1  7O 

83.3 

Laminated  Asbestos  Cork,  sectional   

2.3CK 

81.6 

Asbestos  Air  Cell  (intended),  sectional  f"  Imperial")  

2.46=; 

81.0 

Asbestos  Sponge  Felted,  sectional    

2.68? 

7O.4. 

"  Asbestocell"  (Radial),  sectional    

2.  02O 

77.  e 

Asbestos  Air  Cell  (Long),  sectional     

3.  OI? 

76.8 

Bare  Pipe  (from  outside  tests)                              .        ...        .    .        

I  3.OOO 

Boiler  Feed  Piping.  —  The  size  of  boiler  feed  pipes  is  usually  chosen  for  a  velocity 
of  from  300  to  400  feet  per  minute.  The  entire  feed  pipes  are  made  of  extra  heavy 
material.  The  main  pipes  are  made  of  cast  or  wrought  iron.  To  secure  a  uniform 
standard,  the  flanges  should  be  of  the  same  type  as  that  of  the  main  steam  piping. 
The  main  line  should  be  so  laid  out  as  to  have  either  a  double-header  or  ring  system, 
so  as  to  supply  any  boiler  in  case  of  emergency;  sufficient  valves  should  be  inserted, 
so  as  easily  to  cut  out  defective  sections. 
As  the  temperature  of  the  boiler  feed  water 
is  high,  sometimes  exceeding  212°  Fahr., 
dependent  upon  the  equipment  of  the  plant, 
if  heaters  or  economizers  are  installed  provi- 
sion must  be  made  to  take  up  the  expan- 
sion by  means  of  long  flexible  bends. 

The  branch  pipes  to  the  boilers  are 
generally  supplied  by  the  boiler  manufac- 
turer. These  pipes  are,  in  America,  made 
of  extra  heavy  brass,  while  on  the  Conti- 
nent of  Europe  copper  is  frequently  em- 
ployed. The  practice  of  using  brass  and 
copper  arises  from  the  flexibility  of  those 
metals  and  their  ability  more  readily  to 

take  up  such  shocks  as  are  received  from  the  pumps,  or  from  shutting  down  valves. 
Copper  has  been  used  on  the  Continent  of  Europe  on  account  of  its  high  polish,  not 
because  of  appearance,  but  to  prevent  radiation. 

All  pipes,  such  as  are  not  polished,  as  above  mentioned,  should  be  carefully  cov- 
ered, as  described  under  high-pressure  steam  piping. 

Check  and  hand  valves  should  be  placed  in  each  branch  line,  so  that  the  water 
cannot  return  from  the  boiler  to  the  feed  line  should  the  boiler  pressure  increase  over 
that  in  the  feed  main.  The  check  valve  should  be  placed  between  two  cut-off  valves 
to  facilitate  repairs. 


FIG.  37. 


High-Pressure  Check  Valve  for 
Boiler  Feed  Water. 


216 


STEAM-ELECTRIC   POWER   PLANTS. 


In  order  to  maintain  an  equal  pressure,  the 
main  feed  pipe  is  connected  by  means  of  a  small 
pipe  to  a  pressure  regulator,  inserted  in  the  steam 
pipe  to  the  boiler  feed  pumps.  Should  the  pres- 
sure increase  above  that  required,  the  steam  sup- 
ply will  be  automatically  cut  off  and  the  pump 
slowed  down,  while  when  additional  water  is  re- 
quired the  pumps  start  again  automatically. 

Boiler  Blow-off  Piping.  —  Usually  each  boiler 
is  provided  with  two  blow-off  pipes,  generally  2  J 
inches  in  diameter.  On  some  types  of  boilers 
these  pipes  are  located  directly  in  the  flue  gas 
passage  and  it  is,  therefore,  frequently  necessary 
to  protect  them  by  running  them  through  a  pipe. 
The  blow-off  pipe  should  be  made  of  extra 
heavy  material,  capable  of  withstanding  175  to 
200  pounds  working  pressure.  In  order  that 
FIG.  38.  Fairbanks  Asbestos  the  blow.off  valve  may  be  packed  while  the 
Packed  Blow-Off  Cock.  boiler  .g  in  operationj  an  additional  valve  should 

be  used.     These  valves  are  of  different  types,  one  being  an  asbestos  packed  cock,  the 
other  a  specially  designed  blow-off  valve.     In  selecting  a  blow-off  valve  care  should  be 


FIG.  39.     Morris  Blow-Off  Valve. 

taken  that  there  are  no  projections  or  other  places  for  the  accumulation  of  mud  or  other 
boiler  sediment,  so  that  these  valves  may  not  stick,  but  readily  come  to  a  perfect  seat. 


LOW-PRESSURE  PIPING. 


A  number  of  boilers  may  be  connected  to  one  common  blow-off  header ;  and  since 
generally  but  one  boiler  is  blown  down  at  a  time,  the  diameter  of  this  header  may  be 
three  inches  or  four  inches.  All  branches  should  connect  to  the  header  by  means  of 
a  "Y"  to  minimize  resistance  due  to  mud,  etc.  The  blow-off  line  should  be  made 
of  extra  heavy  wrought  iron  with  provision  made  for  expansion. 

The  size  of  blow-off  tank  depends  on  the  number  of  boilers  connected  to  same. 
In  prominent  plants,  where  twelve  to  eighteen  6oo-horse-power  boilers  are  connected 
to  one  tank,  the  tank  may  be  fron  five  feet  to  six  feet  diameter  and  from  six  feet  to 
eight  feet  high,  and  made  of  rolled  steel,  while  in  smaller  plants  usually  a  horizontal 
tank  three  feet  by  six  feet  is  used. 

The  blow-off  tank  should  be  provided  with  an  overflow  pipe  and  a  vent;  this  latter 
may  discharge  either  directly  to  the  roof  or  to  the  atmospheric  exhaust  pipe,  in  some 
instances  it  is  connected  to  the  auxiliary  exhaust  and  discharge  through  the  heater. 

LOW-PRESSURE    PIPING. 

Under  the  heading  of  low-pressure  pipes  we  may  consider  the  main  exhaust, 
auxiliary  exhaust  and  their  drain  systems,  circulating  water,  vacuum  and  hot  well  suc- 


FIG.  2.     Blake  Horizontal  Automatic 
Exhaust  Relief  Valve. 


FIG.  i.     Blake  Angle  Automatic  Back- 
Pressure  Valve. 


tion  and  discharge,  suction  of  the  boiler  feed  pumps,  suction  and  discharge  of  house 
pump  which  supplies  tanks,  toilets,  fire  line,  etc. 

Size  of  Exhaust  Pipes.  —  In  calculating  the  size  of  the  atmospheric  exhaust  pipes, 
a  velocity  of  from  5,000  to  6,000  feet  is  used,  while  up  to  the  condenser  a  velocity  up 
to  30,000  feet  is  frequently  chosen.  This  high  velocity  is  due  to  the  fact  that,  for 
instance,  a  pound  of  steam  under  a  24-inch  vacuum  contains  118  cubic  feet;  with  three 
pounds  gauge  pressure  a  pound  of  steam  contains  21  \  cubic  feet;  it  is,  therefore,  self- 
evident  that  steam  under  vacuum  being  vastly  rarer  than  steam  above  atmospheric 
pressure  the  friction  is  so  slight  as  not  to  be  taken  into  account. 


218 


STEAM-ELECTRIC   POWER   PLANTS. 


Material.  —  All  pipes  under  vacuum  should  be  absolutely  tight.     For  this  reason 
cast-iron  pipe  is  usually  adopted.     Whenever  long  runs  of  pipe  under  a  vacuum  are 
necessary,  rolled  steel  should  be  used;  all  rivets  and  joints  have 
to  be  securely  caulked  to  avoid  any  leakage.     A  less  frequent 
practice  is  to  use  spiral  riveted  galvanized  pipe. 

The  atmospheric  exhaust,  however,  may  be  of  spiral  riveted 
or  other  light  steel  pipe,  as  it  is  not  subjected  to  much  stress 
and  leakage  is  not  considerable ;  and  as  these  pipes  are  flexible, 
expansion  is  easily  cared  for,  while  in  the  case  of  cast-iron 
pipes,  expansion  joints  may  have  to  be  used. 


Fittings.  —  These  expansion  joints  may  be  either  of  the 
slip-joint  or  corrugated  copper  type,  such  as  the  Wainwright. 
These  joints  may  be  employed  in  low-pressure  piping,  but 
should  never  be  used  with  high  pressure. 

Each  unit  should  be  separately  valved  (either  by  an  auto- 
FIG.  3.     Cyclone    Ex-    ma^c  exhaust  relief  valve  or  a  cut-off  gate  valve)  in  the  con- 
haust   Head.  nections  to  the  main  exhaust,  so  that  it  may  be  cut  out  without 

interfering  with  the  operation  of  the  rest  of  the  plant.      The 

exhaust  riser  should  be  provided  with  an  exhaust  head,  which  acts  as  a  muffler  and 
at  the  same  time  collects  the  water  of  condensation,  which  would  be  a  nuisance  to  the 
surroundings. 

Flanges  for  low-pressure  pipes  should  not  ordin:  >f  special  design,  but  should 


FIG.  4.     "Utility  "  Oil  Extractor  and  Feed-Water  Heater. 


be  standard.     Bolt  or  screwed  flanges  may  be  used  on  large  pipes,  while  on  small  pipes 
screwed  fittings  are  more  convenient  and  cheaper. 


LOW-PRESSURE  PIPING. 


219 


0 

4-> 

00 


CL> 


«&• 


aojiouj 


•OKMeococoTF^t^iOcot-ao 


S 


iC  ••£  (O  I-  GO  O 


cccoTjc*j<iniO5Occi>ooo<-i 


uoipjaj 


UOIPII.I 


'-'OGi—  l'5-- 
(MlMCOCOCOCOCOCO'J'TfTP 


a, 


O 

^  -5 

c    "So 

' 


,0  O 

OJ  fe 

>  6 

^  o 


1& 


X    c 


-S  ffi 


rt 

O 


ci 

U 


OlOOCOCNOO-^rHGCIMCClO 

i«T)<iointo«ot^coo6o-^cc 


Si-(  <N 
Ol^ 


uoipij,} 


COCOCOCOCOOJ 

IMCOTrStCGC 
IIMiMC^IMIMIM 


•ViOtOOI>OOGOO5O(MTj<O 


UOlPiJ.1 


O3!CCO—  GO  1C  <N  O5  CO  r-  rH 
•Hi-Hrli— I  i— li— I  i-l  i— li— IrtC^ 


aoipuj; 


<o  to  i-*  x  os  o  —  (Meomf-i 


COiOOOCOCMrJUOOi 


OOOOOJO^OOi—  11—  iCNCOrr" 


OOO>OrHC«eC'WI>e«: 

i-(i-lf-li-li-li-HT-lfjMCN 


8- 


^-It-l^-ICN  IN  (MINIM  CJCMCOCO 


uoipuj 


SffcSfi9t5e*o05i«ir<n( 


)(MlCt-CNIt-C^ 

_  eS  -^  r-^  os  r-<  co  GO  IM  t^ 

>  O  C*J  CO  ^J1  l^  CO  GO-'Oi  t-4  ^  CO 
«M<MIN!MeN<NCM<NCOCOCO 


dg, 


PE 


uoipijj 


r-l  i-HH  <M  iM  CJ  OJ  IN  CO  CO  T 


^<>rHir^ 

GO  1C  CO  O  5O  r-(  O 


uoipuj 


>CO<OGOr-(Tl<OOi-CVC^OOO 


IflOirtT-lt^COCXMiCt^ 


22O 


STEAM-ELECTRIC   POWER   PLANTS. 


Drips.  —  The  entire  atmospheric  exhaust  line  should  be  properly  drained  by  means 
of  traps  or  water  seals.  The  water  of  condensation,  if  from  a  turbine,  may  be  returned 
directly  to  a  feed- water  tank,  while  if  from  a  reciprocating  engine  it  must  be  wasted 
or  first  separated  from  the  oil,  either  by  means  of  an  oil  extractor  or  a  water  filter. 
Where  the  exhaust  steam,  from  a  reciprocating  engine,  is  used  for  heating,  an  oil 
extractor  should  be  placed  in  the  line.  One  of  the  most  prominent  types  of  grease 
extractors  is  shown  in  Fig.  4. 

Circulating  Water  Piping.  — The  size  of  the  suctions  to  the  house  pumps  and  cir- 
culating pumps  is  calculated  for  a  velocity  of  from  300  to  400  feet  per  minute,  and 
usually  given  by  the  manufacturers.  Where  long  suction  pipes  are  required  and 
priming,  therefore,  is  inconvenient,  it  is  necessary  to  use  foot-valve.  These  foot- 
valves  should  be  provided  with  a  screen  to  guard  against  foreign  material.  Care  should 
be  exercised  to  have  the  pipes  as  tight  as  possible,  in  order  not  to  destroy  the  suction. 
The  pipes  may  be  either  of  cast  iron,  wrought  iron  or  steel.  Either  screwed  or  flanged 
pipes  may  be  used,  according  to  size  and  opinion. 

Vacuum  and  Hot  Well  Piping.  —  The  vacuum  pipe  should  have  as  few  sharp 
bends  as  possible;  long  sweep  bends  of  either  cast  iron  or  steel  should  be  used.  It  is 


FIG.  6.  Newman  Foot-Valve  provided 
with  Section  Pipe  Extension  and 
Double  Screens. 


FIG.  7.     Anderson  Float  Valve. 


of  vital  importance  that  all  joints  be  perfectly  tight,  or  else  a  vacuum  cannot  be  main- 
tained. The  discharge  end  of  the  pump  may  be  connected  to  the  main  exhaust  riser 
outside  of  the  back-pressure  valve. 


LOW-PRESSURE  PIPING. 


221 


Where  the  discharge  of  more  than  one  hot  well  pump  is  connected  to  one  main 
hot  well  pipe  leading  to  the  heater,  each  separate  discharge  should  be  provided  with 
a  cut-off  valve  and  check  to  prevent,  in  case  a  pump  is  shut  down,  the  water  of  another 
backing  into  it. 


FIG.  8.     Pipe  Connection  of  Water  Meter. 

Covering.  —  All  piping,  such  as  auxiliary  exhaust  to  heater,  return  of  drips  and 
the  boiler  feed  suction,  as  well  as  the  heater  itself,  should  be  covered  with  insulating 
material,  similar  to  high-pressure  covering,  but  may  be  of  lower  grade  or  of  less 
thickness. 


CHAPTER  VI. 
PRIME   MOVERS. 

Comparison  of  Engine  and  Turbine.  —  Prime  movers  may  be  classified  as  recipro- 
cating engines  and  turbines.  The  choice  of  either  of  these  types  for  the  station  is  a 
matter  of  opinion;  the  reciprocating  engine  is  the  older  of  the  two  and  is  entirely  out 
of  the  experimental  class,  whereas  the  larger  number  of  turbines  have  not,  as  yet, 
been  thoroughly  developed.  Some  of  the  many  advantages  claimed  for  the  turbine, 
namely,  less  steam  consumption  per  unit  capacity,  ability  to  withstand  continuous 
operation  without  shut-down,  and  ability  to  use  high  temperature  superheated  steam 
are,  in  many  instances,  overrated.  These  possible  advantages  are  more  or  less  offset 
by  the  more  positive  knowledge  possessed  by  the  manufacturers  of  the  action  and  steam 
consumption  of  the  reciprocating  engine. 

As  to  the  steam  consumption  of  the  two  types  there  is  considerable  variation,  hut 
this  variation  is  due  to  the  difference  in  manufacture  rather  than  the  difference  in 
type.  For  instance,  the  average  steam  consumption  of  first-class  Continental  prime 
movers,  both  reciprocating  engines  and  turbines,  is  from  n  to  9  pounds  per  I.H.P, 
hour,  while  English  and  American  prime  movers  have  a  steam  consumption  of  13  to 
ii  pounds  per  I.H.P.  hour.  Of  course,  in  both  cases  there  are  exceptions  where 
lower  steam  consumption  than  the  above  given  is  obtained. 

The  above  figures  represent  average  everyday  operation  of  first-class  plants  of 
their  respective  countries.  The  difference  in  the  steam  consumption  between  the 
American  and  English  prime  movers  and  those  of  the  Continental  type  is  due  to  the 
more  careful  manufacture  of  the  latter.  The  high  requirements  specified  by  the  power 
plant  designer  are  undoubtedly  the  cause  for  this  particular  care  in  manufacture.  It 
is  the  author's  opinion  that  aside  from  any  manufacture,  it  is  within  the  reach  of  the 
pcnver  plant  designer  to  greatly  reduce  the  steam  consumption,  since  the  general  lay- 
out of  the  plant  as  regards  the  relative  location  of  boilers,  engines,  condensers,  etc.,  and 
the  connections  between  same,  is  of  vital  importance.  In  producing  the  most  econom- 
ical arrangement  the  designer  shows  his  versatility  and  capabilities.  After  the  plant 
has  been  erected  its  continued  economical  operation  rests  with  the  management.  The 
plant  designer  should  be  careful  to  specify  prime  movers  of  low  steam  consumption, 
as  it  is  unquestionably  true  that  such  machines  are  also  of  better  manufacture  and  as 
durable  as  any  other  type. 

In  selecting  a  prime  mover,  of  whatever  type,  one  should  be  decided  upon  that  is 
capable  of  withstanding  a  high  degree  of  superheat;  a  prime  mover  cannot  be  classi- 


PRIME  MOVERS. 


223 


fied  as  a  modern  or  up-to-date  engine  that  does  not  conform  to  this  condition.  By  high 
degree  of  superheat,  a  temperature  of  from  600°  Fahr.  to  700°  Fahr.  is  generally 
understood  in  Continental  practice.  It  is  claimed  by  certain  American  manufacturers 
that  turbines  cannot  be  economically  operated  with  more  than  100°  to  150°  Fahr.  of 
superheat  [about  475°  to  525°  Fahr.  total  heat  (depending  on  pressure)].  This 
claim  is  hardly  correct  for  good  design  and  workmanship. 

As  already  pointed  out,  some  makes  of  turbines,  which  have  been  in  the  field  long 


FIG.  i.     Comparison  of  Turbines  and  Reciprocating  Engines  (Power}. 

enough  to  be  of  better  construction,  still  daily  show  defects  and  give  trouble.  There 
^have  been  turbines  installed  within  the  last  few  years  which,  even  with  a  low  temper- 
ature of  superheated  steam  (100°  of  superheat),  would  cease  to  run.  The  expansion 
of  the  turbine  chamber  is  so  unequal  and  the  clearance  between  moving  and  stationary 
buckets  is  minimized  to  such  an  extent  that  the  working  of  the  turbine  will  be  stopped 
or  the  parts  entirely  destroyed.  In  the  latter  case  new  buckets  must  be  installed. 


224 


STEAM-ELECTRIC  POWER  PLANTS. 


It  certainly  would  not  be  in  the  line  of  economy  to  ship  with  each  turbine  thousands  of 
extra  buckets  to  replace  those  which  must  be  ripped  out,  to  say  nothing  of  the  cost  of 
replacing  them  and  the  delay  in  operation.  Some  manufacturers  have  endeavored,  and 
with  excellent  results,  to  correct  these  evils  by  proper  distribution  of  the  metal  of  the 
turbine  chamber,  by  allowing  more  clearance  and  by  reinforcing  the  buckets. 

In  consequence  of  similar  trouble  occurring  in  some  turbines  or  in  consequence 
of  other  trouble  in  connection  with  the  superheater,  the  use  of  superheated  steam  has 
sometimes  been  abandoned  and  saturated  steam  supplied.  In  order  to  facilitate  the 
use  of  saturated  steam  in  such  cases,  an  adjustable  arrangement  has  already  been 
supplied  in  the  design  of  the  turbine,  so  that  the  clearance  between  the  stationary 
and  moving  parts  may  be  regulated  to  accommodate  the  use  of  saturated  steam.  This 
is  a  troublesome  procedure,  and  it  is  understood  that  at  present  other  remedies  are 
being  provided  to  overcome  the  troubles. 

An  advantage  possessed  by  the  turbine  over  the  reciprocating  engine  is  that  it  uses 
considerably  less  oil,  since  there  are  fewer  and  smaller  bearings.  However,  a  large 
amount  of  oil  must  be  circulated  through  the  bearings  properly  to  flush  same.  Another 
very  important  factor  in  favor  of  the  steam  turbine  is  that  the  water  of  condensation 
from  the  surface  condensers  may  be  immediately  sent  to  the  boilers;  with  the  recipro- 
cating engine  the  water  of  condensation  must  first  have  the  cylinder  oil  extracted. 
Another  advantage  is  that  the  turbine  requires  a  lighter  foundation,  as  it  is  practically 
free  from  vibration  and  may,  if  necessary,  be  mounted  on  a  floor  above  the  boiler 
room. 

Fig.  i  shows  plan  and  elevation  of  vertical  engine  and  turbines  drawn  to  the  same 
scale  for  the  purpose  of  comparison,  and  represents  5,000  K.W.  units.  The  center 
illustration  shows  a  Reynolds  horizontal,  vertical,  four-cylinder,  compound  engine. 
On  the  right  hand  a  Curtis  turbine  is  shown  and  on  the  left  hand  a  Parsons.  It  would, 
however,  be  unfair  to  compare  prime  movers  only,  as  the  turbine  is  usually  equipped 
with  much  larger  condensers  and  auxiliary  machinery. 

In  considering,  therefore,  a  comparison  between  the  floor  space  occupied  by  a 
turbine  and  a  reciprocating  engine,  the  actual  space  occupied  by  the  prime  movers, 
condensers  and  auxiliaries  should  alone  be  considered.  The  space  occupied  by  the 
switch-board  should  not  figure  in  the  comparison.  The  following  figures  show  such 
a  comparison  between  a  few  of  the  recent  plants : 


PLANT. 

Square  Feet 
per  K.W. 

TYPE. 

Bow  Road  Station,  London 

0.008 

Horizontal  and  Vertical  Engines 

Fifty-ninth  St.,  New  York    

1.08? 

Vertical  Engines 

Chelsea,  London     

0.413 

Horizontal  Turbines 

Potomac,  ^^ashington                     .        

0.188 

Vertical  Turbines 

Delaware  and  Hudson  Co.,  Mechanicville,  N.Y  

0.561 

5 

Vertical  Turbines 

Size  of  Prime  Movers.  —  The  size  of  prime  movers  depends  upon  the  capacity  of 
the  plant  and  also  on  the  load  factor.     In  selecting,  care  should  be  taken  that  a  unit 


RECIPROCATING  ENGINES.  225 

• 

or  two  (depending  on  size  of  plant)  should  be  kept  in  reserve.  The  practice  is  to  install 
as  large  prime  movers  as  possible.  There  are  to-day  9,000  K.W.  units  (normal  capacity) 
in  operation,  and  it  will  probably  not  be  long  before  12,000  K.W.  units  will  be  intro- 
duced. The  size  of  prime  movers  and  especially  of  the  turbine,  within  reason,  is  not 
limited;  it  must,  however,  be  remembered  that  the  larger  the  unit  the  greater  the 
inconvenience  in  case  of  a  break-down. 

Power  plants  for  railroading  as  well  as  for  lighting  are  subject  to  great  fluctuation 
in  load,  therefore  reserve  units  are  of  special  importance.  In  order  to  reduce  to  the 
greatest  possible  extent  the  number  of  reserve  units,  American  designers  have  intro- 
duced prime  movers  capable  of  withstanding  50  per  cent  overload.  This  practice  has 
to  a  certain  extent  been  adopted  in  Great  Britain,  but  not  on  the  Continent  of  Europe, 
where  the  overload  capacity  amounts  to  20  to  30  per  cent.  It  is  the  author's  opinion 
that  a  prime  mover  designed  for  50  per  cent  overload  is  in  reality  rated  below  its  actual 
normal  output.  The  rated  horse-power  of  a  prime  mover  should  be  that  at  which  it 
operates  most  economically;  it  is  therefore  loss  in  economy  to  underrate  a  prime 
mover,  provided  it  operates  at  full  rated  load.  Practice  shows  that  these  prime 
movers  capable  of  50  per  cent  overload  operate  most  economically  at  about  20  per 
cent  overload. 

The  method  of  obtaining  overload  from  a  reciprocating  engine  is  to  retard  the  cut- 
off, while  with  turbines  a  secondary  valve  admits  high-pressure  steam  to  a  later  point 
in  the  expansion  rings  of  the  turbine. 


RECIPROCATING   ENGINES. 

Classification. — There  are  numerous  forms  and  designs  of  reciprocating  engines. 
If  sufficient  floor  space  is  available,  horizontal  engines  may  be  adopted;  if,  however, 
the  floor  space  is  limited,  those  of  the  vertical  type  may  be  used.  Engines  are  built 
with  either  one,  two,  three  or  four  cylinders  and  are  called  simple,  compound,  triple 
expansion  or  quadruple  expansion,  respectively. 

Engines  are  built  either  right  or  left  hand  —  they  are  classified  differently  by  vari- 
ous manufacturers.  The  majority,  however,  classify  them  as  shown  in  Fig.  2.  Refer- 
ring to  this  diagram,  an  engine  is  "right  hand"  if  the  cylinder  is  on  the  right  hand 
looking  towards  the  fly  wheel  from  the  rear  of  the  engine,  and  vice  versa.  Taking  the 
same  position,  if  the  uppermost  position  of  the  fly  wheel  moves  away  from  the  observer 
the  engine  is  said  to  run  "forward"  or  "over,"  while  if  it  turns  towards  the  observer 
the  engine  runs  "backwards"  or  "under."  If  the  engine  is  cross  compound,  the  high- 
pressure  cylinder  is  alone  taken  into  consideration  when  classifying  as  to  right  or  left 
hand.  These  classifications  apply  to  both  horizontal  and  vertical  engines. 

Engines  are  also  classified  as  low  and  high  speed.  The  low-speed  engines  are 
those  used  for  the  main  generator  units  and  have  a  speed  of  from  70  to  150  R.P.M. 
according  to  size.  High-speed  engines  are  pract  cally  exclusively  used  for  driving 
exciters,  circulating  pumps,  fans,  etc.,  and  they  run  at  from  150  to  400  R.P.M. 


226 


STEAM-ELECTRIC  POWER  PLANTS. 


left.         


Modern  practice  is  to  direct-connect  the  generators  to  the  engines,  thus  doing 
away  with  all  gearing  or  belting;  the  resultant  saving  in  friction  is  considerable  and 
at  the  same  time  the  floor  space  is  reduced. 

Valve  Mechanism.  —  One  of  the 
most  important  features  in  the  suc- 
cessful operation  of  a  reciprocating 
engine  is  the  valve  gearing.  The 
power  plant  designer  in  selecting  an 
engine  should  consider  well  the  type 
of  valve  gearing  and  governing 
device  best  adapted  to  the  plant's 
particular  needs  and  requirements. 
Whichever  type  is  selected,  be  it 
Corliss,  piston  or  gridiron,  etc.,  it 
should  be  able  to  withstand  highly 
superheated  steam.  Within  recent 
years  many  contributors  to  the  tech- 
nical press  have  claimed  that  a 
Corliss  valve  would  not  operate  with 
superheated  steam  so  successfully  as 
a  poppet  valve.  This  claim  in  the 
author's  estimation  is  ungrounded,  as 
it  is  based  principally  on  European 
engines,  equipped  with  poppet  valves 
and  using  highly  superheated  steam, 
and  showing  a  remarkably  low  steam 
consumption.  There  are,  however, 
numerous  examples  of  Corliss  and 
similar  valves  operating  under  the 
same  conditions  with  equally  good  results.  Low  steam  consumption  is  more  a  matter  of 
workmanship  and  the  design  of  the  entire  engine,  than  a  question  of  valve  mechanism. 
It  is  true  that  superheated  steam,  being  rarer  than  saturated  steam,  will  escape 
more  readily  and  therefore  will  require  a  closer  fitting  valve.  When  the  plant  designer 
is  looking  toward  economical  operation,  as  he  always  should  do,  he  will  select  machines 
which  are  the  best  of  their  respective  kinds  and  class. 

In  order  to  throw  an  engine  in  parallel  with  other  engines  already  running,  it  is 
necessary  to  synchronize  the  particular  generator  with  the  others.  This  is  done  in 
well-designed  plants  from  the  main  switchboard.  A  small  motor  controlled  from 
the  switchboard  is  directly  connected  with  the  governor,  which  enables  the  operator 
to  control  the  engine  speed  to  any  desired  point. 

Simple  Engines.  —  The  simple  engine  works  with  limited  expansion;  its  first  cost  is 
low,  but  the  steam  consumption  is  high.  One  of  the  best  engine  manufacturers  gives 


I***-* 


FIG.  2.     Right  and  Left  Hand  Engine. 


RECIPROCATING  ENGINES. 


227 


the  steam  consumption  of  a  simple  engine  at  from  22  to  27^  pounds  per  I.H.P. 
hour,  assuming  a  working  steam  pressure  of  from  70  to  140  pounds.  When  superheated 
steam  is  employed  of  a  total  temperature  of  from  400°  to  650°  Fahr.  the  consumption 
will  be  reduced  from  2.25  to  5  pounds.  These  engines  are  mostly  used  for  small  and 
variable  loads  and  are  frequently  non-condensing.  By  running  these  engines  con- 
densing the  consumption  will  be  reduced  j  to  ^  below  that  of  a  non-condensing  engine. 

If  two  simple  engines  are  connected  to  the  same  shaft,  they  are  called  twin  engines. 
In  this  case  the  crank  shafts  are  usually  placed  at  an  angle  of  90°  from  each  other,  thus 
giving  a  more  uniform  impulse.  Should  a  single  cylinder  engine  be  installed  and  the 
future  load  not  be  known,  a  second  cylinder  may  very  conveniently  be  added  in  this 
manner.  A  more  economical  method  of  accomplishing  the  same  result  would  be  to 
compound  the  engine  by  the  installation  of  a  low-pressure  cylinder. 

Fig.  3  shows  a  simple  engine  of  the  Allis-Chalmers  type,  direct-connected  to  a  gen- 
erator. It  will  be  noticed  that  the  engine  is  provided  with  Corliss  valve  gearing  operated 


FIG.  3.     Direct-Connected  Single  Cylinder  Corliss  Engine. 

by  an  eccentric  on  the  shaft,  the  motion  being  transmitted  to  the  wrist  plate  by  a  rocker 
arm.  The  governor  is  of  the  usual  fly-ball  type,  belted  to  the  main  shaft  and  regulating 
the  cut-off  automatically  as  required.  These  engines  are  manufactured  of  practically 
any  desired  size  and  for  service  as  above  mentioned,  they  may  operate  either  con- 
densing or  non-condensing.  Their  first  cost  is  low,  while  the  operating  cost  naturally 
is  high. 

Compound  Engines.  —  Where  the  load  is  heavy  and  to  secure  a  greater  economy 
of  steam  consumption,  a  compound  engine  may  be  installed.  These  engines  are  either 
cross  compound  or  tandem  compound.  In  the  former  the  cylinders  are  side  by  side; 


228 


STEAM-ELECTRIC  POWER  PLANTS. 


in  the  latter,  one  behind  the  other  with  the  pistons  on  the  same  piston  rod.  The  com- 
pound engine  may  be  supplied  with  a  receiver  into  which  the  exhaust  from  the  high- 
pressure  cylinder  is  discharged,  and  from  which  the  steam  to  the  low-pressure  cylinder 
is  taken.  Sometimes  these  receivers  are  supplied  with  a  steam  coil,  through  which 
boiler-pressure  steam  is  circulated,  for  the  purpose  of  reheating  the  steam  and  prevent- 


FiG.  4.     5000-K.W.  Vertical-Horizontal  Double  Compound  Engine,  as  installed  at  the 
59th  St.  Plant,  New  York.  (Street  Railway  Journal}. 

ing  condensation.  Where  there  are  no  reheating  coils  installed,  it  is  good  practice 
to  steam  jacket  the  low  pressure  cylinder,  for  the  same  reason  as  given  above.  It  does 
act  pay  to  provide  the  high-pressure  cylinders  with  a  steam  jacket. 

If  tandem  compound  engines  are  used  a  wider  engine  room  is  required,  while  where 
cross  compound  engines  are  used  a  longer  engine  room  is  necessary.     There  is  less 


RECIPROCATING  ENGINES.  229 

friction  in  a  tandem  compound  engine  than  in  a  cross  compound,  but  it  requires  a 
heavier  fly  wheel.  The  steam  consumption  of  both  types  (of  best  manufacture)  amounts 
to  about  16.5  to  13  pounds  per  I.H.P.  hour  for  saturated  steam  at  from  90  to 
175  pounds  pressure;  with  the  use  of  superheated  steam  from  500°  to  650°  Fahr.,  these 
figures  are  reduced  by  i  to  3.5  pounds. 

Compound  engines  are  built  either  of  the  vertical  or  horizontal  type  or  a  combination 
of  both.  In  the  latter  case  one  crank  pin  only  is  necessary  —  sometimes  there  are  two 
such  sets  connected  to  the  same  shaft,  with  the  generator  mounted  between;  these 
engines  are  called  double  compound  vertical-horizontal  engines.  Fig.  4  illustrates 
a  type  of  this  class,  known  as  the  "Manhattan"  and  installed  both  at  the  jgth  Street 
and  59th  Street  power  houses  in  New  York.  They  are  manufactured  by  the  Allis- 
Chalmers  Company. 

The  principal  dimensions  of  the  59th  Street  station  engine  (Fig.  4)  are  as  follows: 

High-pressure  cylinders 42" 

Low-pressure  cylinders      86" 

Stroke 60" 

Revolutions  per  minute 75 

Pressure 175  Ib. 

The  high-pressure  cylinders,  which  are  of  the  horizontal  type,  are  provided  with 
poppet  valves,  the  low-pressure  cylinders  are  provided  with  Corliss  valves.  The 
poppet  valves  are  regulated  in  a  similar  manner  to  the  Corliss  valve,  that  is,  by  an 
eccentric  and  a  wrist  plate.  Such  valve  combination  is  a  very  unusual  practice.  This 
engine  is  rated  at  7,500  horse-power  and  capable  of  50  per  cent  overload.  The  best 
steam  consumption  was  had  at  8,000  horse-power  and  was  11.9  pounds  per  I.H.P.  hour. 

Triple  Expansion  Engines.  —  These  engines  are  not  used  to  any  great  extent  in 
stationary  work  in  America,  but  have  been  broadly  adopted  in  Europe,  because  of 
their  lower  steam  consumption.  This  consumption  is  usually  guaranteed  by  first- 
class  manufacturers  to  be  from  12  to  u  pounds  for  saturated  steam;  where  superheated 
steam  is  used  from  400°  to  700°  Fahr.,  the  consumption  will  be  reduced  from  \  to  2\ 
pounds. 

These  engines  are  frequently  built  with  four  cylinders  having  one  high- pressure 
and  one  intermediate  cylinder,  and  two  low-pressure  cylinders.  Their  chief  disadvan- 
tage is  their  increase  in  first  cost.  A  notable  example  of  a  four-cylinder,  triple 
expansion  engine,  as  installed  at  the  "Moabit"  plant  in  Berlin  and  as  manufactured 
by  Sulzer  Bros.,  is  shown  in  Fig.  5. 

This  engine  *  is  6,500  I.H.P.  and  its  dimensions  are  as  follows: 

High-pressure  cylinder 51^* 

Intermediate-pressure  cylinder 6oJ" 

Low-pressure  cylinder 72i* 

Stroke 66|" 

Revolutions  per  minute 83 

*From  the  author's  article  in  the  Engineering  Record,  May  12,  1906:  "The  Equipment  of  Two  Berlin  Power  Plants." 


230  STEAM-ELECTRIC   POWER   PLANTS. 

This  engine,  operating  at  a  pressure  of  12  atmospheres  (176.4  pounds)  and  a  steam 
temperature  of  572°  Fahr.,  develops  as  follows: 

15  per  cent  cut-off 345°  I.H.P 3000  B.H.P. 

23  per  cent  cut-off 447°  I-H.P 4000  B.H.P. 

32  per  cent  cut-off 5490  I.H.P 5000  B.H.P. 

50  per  cent  cut-off 6500  I.H.P 6000  B.H.P. 

The  high-  and  intermediate-pressure  cylinders  are  furthest  from  the  generator, 
thus  facilitating  the  steam  connection  and  avoiding  as  much  as  possible  highly  heated 
parts  close  to  the  generator.  Therefore  the  two  low-pressure  cylinders  are  bolted 
directly  against  the  frame  of  the  crosshead  guides.  Between  the  high-  and  low-pressure 
cylinders  are  distance  pieces,  with  openings  at  the  top  to  allow  access  to  the  stuffing 
boxes.  Heavy  distance  bolts  are  provided  between  the  cylinders  as  shown  in  the 
illustration  to  reinforce  the  frame.  Except  the  high-pressure  cylinder,  all  cylinders, 
including  the  heads,  are  steam  jacketed  and  supplied  with  steam  at  75  pounds  pressure. 
Each  cylinder  possesses  4  four-seated  poppet  valves,  two  valves  are  at  the  bottom 
and  two  at  the  top;  access  to  the  former  is  from  the  basement.  All  valves  are 
operated  from  the  main  shaft  by  means  of  worm  gearing.  The  governor  is  of  the 
Hartung  type. 

The  hollow  engine  shaft  is  supported  on  bearings  22^  inches  in  diameter  and 
45 \  inches  long,  the  central  portion  of  the  shaft  supporting  the  generator  being  in- 
creased to  33^  inches.  On  account  of  the  weight  of  the  revolving  part  of  the  generator, 
the  bearings  are  water  cooled.  This  same  water  also  serves  to  cool  the  lower  parts 
of  the  crosshead  guides.  From  each  crank  is  operated  a  double-acting  air  pump, 
located  in  the  basement,  as  will  be  seen  in  the  illustration.  All  stuffing  boxes  are 
provided  with  United  States  Metallic  Packing. 

Tests  made  on  this  engine  show  under  actual  operating  conditions  and  under 
normal  full  load,  and  with  a  pressure  of  from  177  pounds  to  188  pounds  at  a  tempera- 
ture of  572°  Fahr.,  an  average  steam  consumption  of  4.03  kilograms  (8.806  pounds) 
per  indicated  horse-power  hour. 

Quadruple  Expansion  Engines.  —  Quadruple  expansion  engines,  although  largely 
used  in  marine  work,  are  seldom  employed  in  stationary  work.  However,  a  note- 
worthy example  of  this  type  was  exhibited  at  the  World's  Fair  in  St.  Louis  by  the 
Societe  Anonyme  des  Etablissements  Delaunay  Belleville,  St.  Denis.  It  is  a  six- 
cylinder,  vertical  type  of  1,500  horse-power  capacity  and  direct  connected  to  a  1,000- 
K.W.  generator ;  the  generator  is  connected  on  one  end  of  the  shaft,  while  the  condenser, 
pumps,  air  and  circulating,  are  connected  to  the  opposite  end  of  the  shaft.  See  Fig.  6. 

This  engine  has  one  high-pressure  cylinder  located  in  the  center,  two  first  inter- 
mediate cylinders  located  on  both  sides  of  the  former  one,  a  second  intermediate 
cylinder  located  in  the  center,  directly  below  the  high-pressure  cylinder  and  between 
the  two  low-pressure  cylinders. 


-----i      / 

•s.-^i* Js '     / 


FIG.  5.  Sulzer,  Four  Cylinder,  Triple  Expansion,  Superheated 
Steam  Engine  (4700  K.W.)  as  installed  at  the  Moabit  Plant, 
Berlin,  operating  at  Normal  Full  Load  with  a  Steam  Con- 
sumption of  9.1  Ibs.  per  I.H.P.  hour. 


F    THE 

UNIVERSITY 

OF 


TURBINES.  231 

The  dimensions  of  this  engine  are  as  follows: 

High-pressure  cylinder J3I" 

First  intermediate-pressure  cylinder I3$" 

Second  intermediate-pressure  cylinder 26|" 

Low-pressure  cylinder 26|" 

Stroke 17^" 

This  engine  is  designed  for  an  initial  pressure  of  300  pounds  and  a  total  steam 
temperature  of  750°  Fahr.     It  will  be  noticed  that  none  of  the  cylinders  are  jacketed. 


FIG.  6.     Six  Cylinder,  Quadruple  Expansion,  High  Speed  Engine  (1000  K.W.). 

The  valves  are  of  the  piston  type.     Although  this  engine  may  not  be  adaptable  to 
general  power  plant  practice,  it  is  an  interesting  example  of  its  class. 


TURBINES. 

Classification.  —  Steam  turbines  may  be  classified  as  impulse  and  reaction.  The 
former  may  be  sub-classified  as  single  impulse  and  compound  impulse.  In  the  impulse 
type  the  steam  expands  either  in  a  nozzle  or  in  the  stationary  vanes,  or  both.  In  the 
reaction  type  the  steam  expands  in  the  rotating  vanes. 


232 


STEAM-ELECTRIC   POWER  PLANTS. 


The  single  impulse  type  is  represented  by  the  De  Laval  turbine,  the  multiple 
impulse  types  are  turbines  such  as  the  Curtis,  Rateau,  Zoelly,  etc.  The  Parsons  tur- 
bine, as  manufactured  by  various  concerns,  is  the  only  one  of  the  reaction  type.  There 
are  also  turbines  of  the  combined  impulse  and  reaction  type,  such  as  the  Terry  and 
Sulzer. 


FIG.  7.     De  Laval  Turbine. 

Single  Impulse  Turbines.  —  The  single  impulse  turbine  (De  Laval),  which  may 
also  be  classified  as  single  stage  type,  is  shown  in  Fig.  7.  It  consists  of  a 
single  wheel,  mounted  on  a  flexible  shaft;  has  an  extremely  high  velocity,  amounting 


TURBINES. 


233 


with  a  5-K.W.  turbine  to  30,000  R.P.M. ,  while  with  a  200-K.W.  turbine  the  velocity  is  as 
high  as  10,000  R.P.M.     This  type  of  turbine  is  rarely  built  larger  than  200  K.W.  capa- 
city.   The  high  velocity  of  these  turbines  requires  that  when  using  them  for  commercial 
purposes    gearing    has    to   be   em- 
ployed.    These  gears  are  made  of 
solid    cast    steel    or    iron.      "When 
connected  to  generators,  there  are 
usually    two    generators    in    a    set 
rotating  in  opposite  directions.     In 
power-house    work    these    turbines 
may     be     employed     for    blowers, 
centrifugal  pumps,  etc. 

The  action  of  the  turbine  is  as 
follows : 

The  steam,  after  passing  the 
throttle,  enters  a  number  of  ex- 
pansion nozzles  in  which  the  steam 
is  completely  expanded  in  passing 
to  the  buckets,  thus  transferring 
the  kinetic  energy  to  the  turbine 
wheel,  from  which  it  passes  to  the 
exhaust  opening. 


Compound  Impulse  Turbines.— 

The  compound  impulse  turbine 
consists  of  two  or  more  stages,  the 
steam  passing  successively  from  one 
to  the  other,  finally  discharging 
through  the  exhaust  port.  The 
Curtis  turbine,  which  is  the  most 
successful  in  use  in  America,  is 
built  on  this  principle.  The  earlier 
styles  were  of  the  two-stage  type, 
while  in  the  present  design  four 
stages  are  employed. 

This  Curtis  turbine  is  built  both         FIG.  8. 
vertical  and  horizontal.      The  for- 
mer are  practically  exclusively  used 

for  the  main  generator  units,  while  the  latter  are  built  of  smaller  capacity  and 
may  be  used  for  exciters.  As  will  be  seen  in  Fig.  8,  which  shows  a  four-stage 
vertical  Curtis  turbine,  the  generator  is  mounted  on  top  of  the  turbine  directly 
connected  to  the  shaft,  the  latter  resting  in  an  adjustable  step  bearing.  Oil  is  supplied 
to  the  step  bearing  by  high-pressure  pumps,  so  that  when  the  turbine  is  in  operation 


Half  Cross-Section  of  Curtis  Turbine 
and  Generator. 


234 


STEAM-ELECTRIC  POWER  PLANTS. 


the  shaft  revolves  upon  a  film  of  oil.  Provision  is  made  so  that  a  continuous  flow  of 
oil  will  always  be  preserved,  either  by  means  of  duplicate  pumps  or  else  by  the  use  of 
an  accumulator,  as  will  be  seen  in  an  article  on  oiling  system. 

Steam  is  admitted  to  the  first  stage  through  a  number  of  pilot  valves  automatically 
controlled  by  a  single  governing  device,  from  which  it  passes  successively  to  the  buckets 
of  the  wheels,  expanding  in  same,  and  passing  the  diaphragms,  which  are  placed 
between  the  rotating  wheels.  Unlike  many  other  turbines,  the  buckets  are  not  riveted 
or  caulked  to  the  wheel,  but  are  milled  out  of  solid  discs,  thus  entirely  eliminating  the 
possibility  of  rupture  in  this  part  of  the  turbine.  A  great  number  of  these  turbines 
have  been  installed  in  the  more  prominent  plants  in  America,  the  largest  types  of 
which,  at  present,  are  of  9,000  K.W.  normal  capacity.  Turbines  of  this  size  are  installed 
in  the  Fisk  Street  station  of  the  Commonwealth  Electric  Power  Company  of  Chicago, 
111.,  where  also  four  5,ooo-K.W.  units  are  installed. 

A  series  of  tests  were  made  on  one  of  these  5,000  K.W.  units,  a  report  of  which  is 
as  follows: 

All  the  tests,  except  the  speed  tests,  were  made  under  regular  commercial  load 
conditions.  On  account  of  the  change  in  frequency  in  the  speed  tests  the  load  was 

TABLE  I. 


Load  Kw. 

B.  P.  M 

WAThR  RATK-Lbs.  Per  Kw.  Hr. 

Note. 

Actual 

Superheat,  p)$  in. 
Back  Pressure 
175  Ibs.  Steam' 

3340 

171 

151 

56690 

1070 

89 

500 

.16.66 

17.29 

Water  Rheostat 

5940 

•169 

180 

98370 

950 

1.72 

" 

16.40 

1655 

Commercial 

3920 

172 

«58 

5°93° 

1050 

1.08 

" 

17.08 

17.61 

Commercial 

4860 

'79 

I  So 

8  '550 

1700 

i-55 

" 

16.50 

16.81 

Water  Rheostat 

7525 

'75. 

«47 

130200 

820 

2.09 

17.19 

16.91 

Water  Rheostat 

4950 

1  80 

I?' 

80570 

220 

1.48 

" 

16.23 

'6-55 

Commercial 

0. 

178 

150 

3520      = 

220 

1.40 

Full  Voltage 

TABLE  II. 


l.'.a  1  Kw. 

' 

Steam 
(Gauge) 

Superheat 

Gross  Plow. 
Pounds  Per 
Hour.. 

Leakage,  Pounds 
Per  Hour 

Back  Pressure 
Inches  Mercury 

R.  P.  M. 

WVTKB  RATE—  Ubs.  Per  Kw.  Hr, 

NotM 

Actual  ' 

Reduced  to  •«>« 
SniK-rheat.  1%  in. 
Back  Pressure. 
•75  UPS.  Steam 

6<o  R.  P.  M. 

*353P 

170 

I65 

55900 

1O7O 

-85 

650 

'5-55 

16.40 

Water  Rheostat 

5'40 

.l80 

'79 

81930 

I7OO 

1-50 

640 

'5-&7 

16.03 

Water  Rheostat 

8090 

'77 

141 

131l60 

820 

2.03 

640 

1  6  ii 

15.80 

Water  Rheostat 

Average  of  two  points. 


Test  of  5000-K.W.  Curtis  Turbine  at  Fisk  St.  Plant,  Chicago. 


absorbed  by  plates  in  the  Chicago  River.  It  was  found  that  for  a  given  load  the  com- 
mercial load  water  rate  was  identical  with  that  obtained  by  the  use  of  a  water  rheostat, 
other  conditions  remaining  the  same. 


TURBINES.  235 

In  the  commercial  tests  a  constant  load  was  maintained  on  the  turbine  under  test 
by  varying  the  tension  of  the  auxiliary  governor  spring,  controlled  by  a  motor  at  the 
switchboard.  Steam  pressure  and  superheat  were  kept  as  nearly  constant  as  possible 
by  proper  attention  at  the  boilers. 

All  tests  were  made  at  about  150°  superheat.  The  temperature  was  read  by  cali- 
brated mercury  thermometers  placed  in  wells  filled  with  mercury  and  correction  was 
made  for  the  exposed  stem.  The  temperature  and  pressures  were  read  every  five 
minutes. 

The  amount  of  steam  was  obtained  by  discharging  the  condensed  steam  into 
tanks  where  it  was  weighed.  After  each  run  the  condenser  was  tested  for  leaks,  which, 
as  shown  by  the  tables,  were  of  small  amount. 

The  result  of  the  tests  are  shown  in  Tables  I,  II,  III  and  IV.  To  make  the  tests 
comparable,  all  results  were  reduced  to  150°  superheat,  i  J  inches  back  pressure,  and  175 
pounds  (gauge)  steam  pressure.  The  actual  and  the  reduced  water  rates  are  given  in 
the  table: 

TABLE  III. 

SUMMARY  OF  TABLE  I. 

500  R.P.M. 

150  Degrees  Superheat. 

1 1  Inches  Back  Pressure. 
175  Ibs.  Steam  Pressure  (gauge). 

LOAD.                                                                                                                                 WATER  RATE. 
2500  K.W.  (i        Load)       !7-74 

3750     "     (!        "   )     17-08 

5000      "      (Full      "     )      16.62 

6250      "      (ij         "     )      16.52 

75°°      "      (Ji        "    )      l6-9° 

TABLE  IV. 

SUMMARY  OF  TABLE  II. 
650  R.P.M. 
150  Degrees  Superheat. 

ij  Inches  Back  Pressure. 
175  Ibs.  Steam  Pressure  (gauge). 

LOAD.  WATER  RATE. 

3750  K.W.  (I        Load) 16.35 

5000      "      (Full     "    ) 16.07 

6250      "      (il         "    ) 15.88 

7500      "      (ij         "     ) 15.80 

The  Rateau  turbine,  similar  to  the  Curtis,  is  also  of  the  compound  impulse  type; 
as  this  turbine  consists  of  a  large  number  of  wheels,  it  is  frequently  called  multiple 
impulse.  The  sectional  view,  Fig.  9,  represents  this  turbine  as  manufactured  by 
Sautter,  Harle  &  Co.,  Paris.  This  particular  design  is  arranged  in  two  separate 
cylinders,  thus  enabling  a  bearing  to  be  placed  between  the  two.  Frequently,  however, 
the  entire  rotating  part  is  enclosed  in  a  single  cylinder. 


236 


STEAM-ELECTRIC    POWER    PLANTS. 


O 

U 


c 
rt 

vy 
"H 
rt 

ffi 


OH 
OJ 


<u 
d 

1 


vJR  5> 

/i 

I   UNIVERSI"1" 


TABLE  L  —  TESTS  OF  WESTING 


SlZ»  OF  TURBINE. 


VACUUM  IN  EXHAUST  . 


26  Inches. 


[THROTTLE  PRESSURE  LBS.  GAUGE  , 


125 


CONDITION  or  THE  STEAM 


Dry  and  Saturated 


140 


Quality  =  99*. 


Dry  and  Saturated 


150 


27! 


Dry  and  Saturated. 


REVOLUTIONS  PER  MINUTE. 


3,600 


3,600 


3,600 


3,000 


TURBINE  NUMBER. 


35 


47 


49 


55 


Steam  pressure  Ibs.  per  gauge 

Vacuum  referred  to  30-inch  barometer. 

Superheat,  degrees  Fahrenheit 

Quality  or  the  steam 

Revolutions  per  minute 


126.6  134.9 


26.0 
2.5 


3.536 


Load  in  kilo-watts 

Load  la  electrical  horse-power  .  ... 

Load  in  brake  horse-power 

Total  pounds  of  steam  per  boor .... 
Pounds  of  steam  per  B.  H.  P.  hour. 
Pounds  of  steam  per  B.  H.  P.  hour. 

Load  In  per  cent,  of  full  load 


580.1 
8,940 


15.41 


2«.02 


3,555 


457.2 
7,481 


16.36 

77 


130.6 
26.03 


142.8144.0144.5138.2151 
26.0   26.0   26.0   26.0 


3,545 


.989 
3,511 


6,834 


9,502 


17.89 
55 


105 


.989 
3,557 


326.0  523. 4  508.2  381.0 


7,992 


15.24  15.73  16.56 


3,582 


6,311 


64 


.6 

26.06 


3,589 


1.00 
3,541 


610.8 
8,917 


14.59 
103 


151.4 


3,599 


451.4 
6,916 


15.32 

77 


149.8 


153.4 

27.04 


3,593 


1.00 
3,528 

438.1 


266.1 
4,54? 


17.06 
45 


8,739 
14.89 


109 


10 


It 


153.2   153.1     152 
27.11    27.0687.15 


3,576 
898.4 


400.0 


6,205 
15.51 


75 


3,583 
211.6 


3,530 


283.6 


4,774 


9,200 


53 


156 
27.2 


3,565 


435 
6,472 


14.1514.88 


152 


25  27.01  27.01 


.997 
3,577 


1.00 
3,497 


261 
4,411 


9,7*1 


16.9 
44 

10 


119 


155 


140.'.)  U* 


1.00 


27.0 


3,M9  3,541 


27 


3,5. 


691  593. 5  607. T 


8,514 


8,382 


14.1  14.  i'. 


S.I 


100 


IS 


10:1 


19      20 


<3izx  or  TURBINE. 


400  K.W. 


1,000  K.  W. 


VACUUM  IN  EXHAUST  . 


28  Inches. 


27  Inches. 


TIIBOTTLB  PBBBSUEB  LBS.  GAUSS. 


150 


130 


150 


CONDITION  or  THS  STEAM  . 


100°  Superheat. 


150°  Superheat.      180°  Superb 


190°  Superheat. 


Quality  =  100*. 


Quality  = 


RBYOLUTTONB  PBR  MINUTB. 


8,600 


3,600 


3,600 


3,600 


1,500 


1,50« 


TURBINB  NCMBBB. 


55 


54 


67 


Steam  pressure  Ibs.  per  Range 

Vacuum  referred  to  80-inch  oarometer. 

Superheat,  degrees  Fahrenheit 

Quality  of  the  steam 

Revolutions  per  minute 


150 

28.01 

104 


3,458 


Load  In  kilo- watts 

Load  in  electrical  horse-power 

Load  in  brake  horse-power 

Total  pounds  of  steam  per  hour 

Pounds  of  steam  per  E.  H.  P.  hour. 
Pounds  of  steam  per  B.  H.  P.  hour. 

Load  in  per  cent,  of  fall  load 


759 
9,167 


12.06 

123 


44 


150.3 

28.01 

104 


3,544 


7,408 


12.5 
100 


154.6 
28.01 


3,581 


5,728 


12.87 
75 


4<J 


28.01 


150.6 
28.0 
139 


8,627 


3,538 


3,504 


7,426 


14.48 
45 


11.86 
106 


47 


43 


149.4 
28.0 
158.8 


3,580 


5,324 


11.87 

76 


40 


28.0 
150 


28.08 
182 


3,595 


3,478 


296.8 
3,919 


763 
8,520 


13.2 
50 


11.17 
129 


51 


153.6 
28.1 
180 


148.4 
28.0 
192 


3,543 


3,551 


428.4 
571.5 


6,795 


100 


7,444 
13.02 


106 


63 


147.9 
28.0 
185 


3,571 

303.8 
407.2 


5,626 
13.81 


76 


149.1 
28.0 
157 


132.5 
27.02 


3,583 

197.8 
285.1 


1,489 

1,101.7 
1,476.8 


4,128 
15.56 


50 


21,984 
14.9 


110 


132.7 
27.0 


1,498 

786.7 
1,054.5 


16,867 
16.99 


79 


134.3 

27.06 


1,508 

630.7 
711.4 


12,775 
17.95 


63 


139 


148.7 


1,518 


.98 


150.: 


10,547 
20.75 


38 


32,924  23,0: 


120 


BUM  or  TUBBINB. 


1,250  K.W. 


VACUUM  IN  EXHAUST. 


28  Inches. 


25  Inches.    26  Inches 


27  Inches. 


THROTTLB  PRESSURB  LBS.  GAUGE. 


150 


150 


160 


CONDITION  or  STEAM. 


140"  Superheat. 


Dry  Saturated 


Dry  Satnr'd. 


Dry  Saturated. 


REVOLUTIONS  PER  MINUTB  . 


1,600 


1,200 


1,200 


1,200 


TURBINE  NUMBER  . 


17 


43 


43 


41 


Steam  pressure  Ibs.  per  gauge 

Vacuum  referred  to  30-inch  barometer. 

Superheat,  degrees  Fahrenheit 

",uality  of  the  steam ; 

evolutions  per  minute 


154 

is.l 
141 


Load  in  kilo-watts 

Load  in  electrical  horse-power. 

Load  in  brake  horse-power. . .- 

Total  pounds  of  steam  per  hour. . . . 
Pounds  of  steam  per  E.  H.  P.  hour. 
Pounds  of  steam  per  B.  H.  P.  hour . 

Load  in  per  cent,  of  fall  load 


1,600 

1.513 
2,030 

26,685 
12.66 


121 


86 


28.04 
139 


1,600 

904 
1,210 


72 


87 


148.9 

28.17 

138 


146.4 
25.01 
2 


1.503 


8,108 
19.68 


1,199 


2,008.3 
28,902 


24 


14.39 
110 


89 


143.4 
25.05 
3 


147 

26.01 


1,201 


1,198 


1,004.4 
16,809 


2,002.3 
28, 


16.73 
55 


14.10 
110 


91 


148.9 
26.05 


141.8 

20.79 


1.00 
1,202 


1,007 
16,106 


15.99 
55 


1.00 
1,197.4 


1,988.9 
2,666 


40,647 
15.21 


159 


93 


144.5 
26..05 


1.00 
1,200 


1,713.6 
2,297.1 


33,036 
14.88 


137 


94 


14*8 
27.05 


1.00 
1,201 


1,489.4 
1,996.5 


28,208 
14.13 


119 


95 


147.1 
27.11 


1.00 
1,196 


1,321.5 
1,771.4 


25,712 
14.52 


106 


96 


MM 

27.11 


1. 00 
1,197 


989.5 
1,326.5 


20,254 
15.27 


97 


146.8 
87.11 


1  00 
1,199 


656 
87U.3 


15,074 
17.14 


53 


151.4 
27.1 


1.00 
1,201 


312.7 
459.4 


•  9,732 
21.18 


160.3 

27.08 


.999 
1,201 


7,150 
27.08 


146.3 
27 
9 

U99 


2.005.  S 
27,248 


110 


100 


101 


•  Test  made  by  Mr.  F.  W.  Dean  of  Dean  A  Main,  Boston. 


t  Tests  made  by  «  board  of  naval  engineers. 


NTGHOUSE-PARSONS  STEAM  TURBINES. 


400  K.  W. 


28  Inches. 

27  Inchei. 

150 

150 

5°  Superheat. 

100°  Superheat. 

Dry  Saturated. 

45°  Superheat. 

3,600 

3,600 

3,600 

3,600 

53 

37 

39 

55 

36- 

52 

148.8 
27.0 
5.0 

154 
27 
4 

153.5 
27.0 
2.0 

154 
27 

149.8 
27.01 
100 

160.6 
27.0 
103.5 

152.8 
27.0 
95.6 

155.2 
27.05 
97.6 

147.5 
97.0 
104.2 

155 
27 
103.1 

1W.6 
28.01 

154,5 

27.98 

156 
27.92 

156.8 
28.01 

152 
28.01 

151.7 
28.0 

154.5 
28.0 

153 
28 

143.5 
27.78 
45.0 

149.6 
88.03 
44.0 

150.3 
28.0 
42.0 

152.1 
28.01 
45.0 

150.7 
28.02 
41.0 

150 
28.02 

45.0 

1.00 

.999 

1.00 

.996 

.986 

.992 

.992 

i.66 

3,563 

3,564 

3,583 

3,602 

'3,492 

3,570 

3,606 

3,482 

3,509 

3,530 

3,480 

3,545 

3,583 

3,602 

3,662 

3,528 

3,570 

3,591 

3,414 

3,436 

3,478 

3,511 

3,526 

3,549 

411.2 

311.7 

219 

402 

292.2 

198.7 

•••••••• 

....... 









•  •  •  •  * 

893  7 

539 

391.7 

266.3 

441.2 
6,625 

288.9 
4,774 

iisie 

2,881 

"o'i 

953.5 

'650'.3 
8,778 

""48i 
6,657 

254.4 
4,039.5 

729 
9,928 

593.2 
8,269 

its 
6,488 

241 

3,876. 

6.3 

706 

-  1,028.2 
14,537 

824.6 
11,020 

755.9 
9,998 

621.5 
8,417 

424.6 
6,015 

258.1 
4,015 

7,425 
13  47 

5,780 
13  83 

4,272 
14.54 

8,169 
15.15 

6,172 
15.76 

4,640 
17.48 

is]oi 

i(i!52 

18.88 

13.5 

13.84 

15.87 

13.62 

13.91 

14.48 

18.05 

14.18 

13.36 

13.23 

13.S6 

14.16 

15.55 

75 

49 

26 



110 

82 

43 

103 

78 

55 

123 

100 

76 

41 

1 

100 

73 

50 

174 

140 

129 

106 

79 

44 

20 

21 

22 

23 

24 

25 

26 

27 

28 

29 

30 

31 

82 

33 

84 

85 

36 

87 

38 

89 

40 

41 

42 

48 

1.250K.  W. 


Inches. 

26  Inches. 

27  Inches. 

27.5  Inches. 

28  Inche?. 

150 

150 

150 

150 

150 

.ity  =  98*. 

Quality  =  98*. 

Quality  =  98*. 

Quality  =  99*. 

50°  Superheat. 

Dry  Steam. 

25°  Superheat. 

Quality  =  98*. 

1,500 

1,500 

1,500 

1,200 

1,500 

1,600 

1,500 

1,500 

17 

17 

17 

32 

17 

31 

31 

.17 

150.5 
25.08 

151 
25.18 

150.5 
26.05 

'  150 
25.92 

151 
26.22 

147 
26.93 

150.4 
26.99 

148 
26.87 

147.7 
27.05 

146.5 
27.06 

148.6 
27.07 

149.2 
27.08 

149.8 
27.01 
50  0 

149.6 
26.92 
51.0 

149.5 
27.06 
49.0 

151 
26.68 
54.0 

t 
149.4 
27.5 

t 
146.2 
X  .85 

146 

27.48 
28 

"l,476 

1,557.6 
2,087.8 

144.3 
27.52 
28 

"1,491 

1,239.8 
1,662 

147.6 
27.46 
28 

"l,503 

767.9 
1,028.1 

155.1 
27.55 
30 

'i',607 

383.4 
513.9 

148.8 
27.42 

ISO 
28.12 

151.8 
28.98 

.98 

1,503 

914 
1,224 

.98 
1,500 

310 
417 

.98 
1,503 

1,519 
2,038 

.98 
1,503 

897 
1,201 

.98 
1,500 

306 
410 

.98 
1,495 

1,629 
2,050 

.98 
1,502 

963 
1,285 

.98 
1,500 

254 
340 

.992 
1,186 

1,630.2 
2,051.2 

.994 
1,203 

1,154.5 
1,647.8 

.992 
1,206 

792.1 
1,061.6 

.991 
1,221 

392.5 
626.1 

'i',502 

1,475 
1,978 

T.503 

1,253 

1,681 

'  i',500 

877 
1,178 

T,5o6 

302 
406 

.994 
1,456 

1,510.4 
2,024.6 

.995 
1,477 

1,019.1 
1,365 

.988 
1,499 

1,546 
2,065 

.975 

1,502 

935 
1,252 

.979 
1,500 

262 
249.2 

23,030 

18.82 

11,713 
28.1 

32,039 
15.72 

21,985 
18.29 

10,891 
26.62 

31,192 
15.22 

21,918 
17.06 

9,109 
26.79 

30,358 
14.8 

23,233 
15.01 

18,273 
17.21 

10,625 
20.19 

27,246 
13.82 

24,544 
14.6 

19,223 
16.35 

9,773 
24.2 

28,333 
13.99 

20,915 
15.31 

28,537 
18.67 

23,181 
13.94 

16,507 
16.05 

10,802 
20.04 

3,456 
14.73 

19,703 
16.75 

7,392 
21.6 

73 

25 

121 

72 

24 

122 

77 

20 

123 

92 

63 

31 

118 

100 

70 

24 

120 

81 

125 

99 

61 

81 

124 

76 

2/ 

86 

61 

62 

68 

64 

65 

66 

67 

68 

69 

70 

71 

72 

73 

74 

76 

76 

77 

78 

79 

80 

81 

83 

H 

84 

1,250  K.  W. 

2,600  K.  W.  $ 

28  Inches. 

27.5  Inches. 

150 

190 

75°  Superheat. 

Dry  Saturated. 

75°  Superheat. 

100°  Superheat. 

190°  Superheat. 

1,500 

1,200 

1,200 

1,200 

1,200 

1,360 

43 

41 

41 

43 

41 

43 

).3 

145.9 
27 
2 

148.7 
26.95 
2 

t 
146.3 
27.1 
76 

147.7 
27.1 
76 

ill 
27.15 
77 

151.9 
27.07 
7? 

151.8 
27.15 

77 

146.1 
28.08 

146.8 
28.1 

1*51 
28.05 

146.9 
28.1 
2 

149 
28 
2 

146 
28.1 

78 

147.6 
28.1 
77 

150.8 
28.05 
77 

151.8 
28.05 
76 

147 
7,  .95 
102.3 

146.4 
28.02 
104 

147.2 
27.97 
102.3 

148.8 
28.02 
102 

188 
27 
214 

188 
27.5 
180 

186 

27.98t 
186 

1  00 

1  00 

1  00 

199 

1,199 

1,202 

1,201 

1,293.9 
1,734.4 

"23,6n3 
13.78 

104 

1,205 

986.2 
I,3a2 

ib'.ios 

14.45 
79 

1,209 

664.7 
891 

14,18$ 
15.9 

53 

1,213 

833.6 
447.1 

'9,176 
20.51 

27 

1,201 

191 
256 

'  6,734 
26.3 

15 

1,197 

1,364 
1,828.3 

"25,639 
14.02 

109 

1,201 

972 
1,303 

19.334 
14.91 

78 

1,198 

334.8 
448.7 

'9,295 
20.71 

27 

1,200 

1,204 

1,199 

1,274.2 
1,708 

"22',504 
13.17 

102 

1,204 

977.6 
1,310.5 

"'18480 
13.87 

78 

1,214 

333.2 
446.6 

'  8,420 
18.86 

27 

1,217 

198.4 
266.1 

'6,300 
23.68 

16 

1,203 

1,202 

1,203 

1,199 

1,360 

2,905 
4,010 

44,236 
11.02 

115 

1,360 

2,518 
3,378 

30,856 
11.57 

97 

1,360 

1,945 
2,608 

'30,867, 
11.83 

75 

5.3 

248 

!59 
0 

1,499.7 
21,189 

"iiiis 

82 

I,6fl4 
15,241 

'isiis 

55 

1,578.2 
21,286 

'"is'.'ig 

87 

911.5 
13,337 

"u'.63 
50 

1,808 
23,180 

'l2!82 
99 

1,655.8 
21,302 

"i^Se 
90 

1,298.4 
17,009 

"isiog 

71 

815.4 
11,671 

'is.io 

34 

1 

102 

103 

104 

105 

IOC 

107 

10$ 

f  ,'09 

110 

111 

112 

113 

114 

115 

116 

117 

118 

119 

120 

121 

122 

123 

124 

J  Tests  witnessed  and  verified  by  engineers  of  the  staff  of  Julian  Kennedy,  Pittwburg,  Ta. 


§  Built  by  the  Brown-Boreri  Company. 


TURBINES. 


237 


1 

^ 


en 
O 

•a 

.2 

en 

<u 

^ 


<u 
C/3 


238 


STEAM-ELECTRIC   POWER   PLANTS. 


Reaction  Turbines.  —  Fig.  10  is  a  section  of  a  Parsons  turbine  as  manufactured  by  the 
Westinghouse  Company,  of  Pittsburg,  which  varies  in  several  details  from  other  Parsons 
turbines  manufactured  by  other  concerns  in  America  and  Europe.  This  Parsons  or 
reaction  turbine  is  so  well  known  that  it  is  not  necessary  to  give  a  detailed  descrip- 
tion. On  one  end  of  the  shaft  there  are  a  number  of  pistons  so  arranged  that  they 
will  balance  the  pressure  and  remove  the  thrust  from  the  rotary.  These  pistons  are 
not  used  in  the  British  Westinghouse  Parsons  turbine,  where  the  steam  enters  in  the 


FIG.  ii.     35OO-K.W.  Turbo  Alternator,  Neasden  Plant,  London. 


center  of  the  turbine  case,  expanding  on  both  sides  towards  the  exhaust  ports  and 
forming  in  reality  a  double  turbine.     See  Fig   n. 

The  Brown-Boveri  Company,  Baden,  Switzerland,  succeeded  first  in  building  the 
Parsons  turbine  to  operate  with  a  remarkably  low  steam  consumption.  One  of  the 
most  notable  earlier  installations  is  that  of  the  municipal  light  &  power  plant  of 
Frankfurt,  \vhere  the  steam  consumption  amounts  to  9.11  pounds  per  I.H.P.  hour 
under  actual  working  conditions,  operating  with  162  pounds  pressure  and  572°  Fahr. 
and  approximately  28  inches  vacuum.  Fig.  12  shows  a  Brown-Boveri  Parsons  turbine 
of  6,500  K.W.  capacity,  as  installed  in  the  light  and  power  station  in  Essen,  Germany. 
It  has  one  5,ooo-K.W.  A.C.  generator  and  one  i,5oo-K.W.  D.C.  generator  and  the 
exciter  mounted  on  the  main  turbine  shaft.  The  entire  length  of  the  unit  is  65  feet  and 


TURBINES. 


239 


its  greatest  width  over  all  is  8.5  feet,  while  the  highest  point  is  8.5  feet  above  the  top 
of  the  bedplate.     The  guaranteed  steam  consumption  of  this  turbine  of  which  there  are 


FIG.  12.     65<Do-K.W.  Brown,  Boveri  Parsons  Turbo-Generator  at  a  Plant  in  Essen,  Germany. 

two  installed,  exhausting  to  one  surface  condenser,  is  8.8  pounds  per  I.H.P.  hour  with 
175  pounds  pressure,  570°  Fahr.  total  temperature  and  not  less  than  27  inches  vacuum. 


FIG.  13.     Brown,  Boveri  Parsons  Turbine  with  Casing  removed. 

These  turbines  are  usually  equipped  with  their  own  auxiliary  machinery,  motor  driven, 
which  operates  with  1.5  per  cent  of  the  total  output,  bringing  the  total  steam  consump- 
tion up  to  approximately  9  pounds  per  I.H.P.  hour. 


240 


STEAM-ELECTRIC   POWER   PLANTS. 


As  has  already  been  stated  in  the  introduction  of  this  article,  the  Parsons  turbine  as 
well  as  several  other  types  of  turbines  are  provided  with  a  secondary  valve,  admitting 
high-pressure  steam  to  a  later  point  in  the  expansion  rings  of  the  turbine,  thus  increas- 
ing the  total  output  of  the  machine.  By  so  doing  the  steam  consumption  is,  however, 
increased. 

CONDENSERS. 

Principle.  —  The  economy  of  a  prime  mover  is  increased  as  the  temperature  of  the 
exhaust  steam  is  reduced.  If  the  exhaust  is  carried  directly  into  the  atmosphere,  the 
ideal  back  pressure  will  be  14.7  pounds  per  square  inch  at 
sea  level,  or  212°  Fahr. ;  if,  however,  exhaust  is  carried  into 
a  vacuum,  produced  by  an  auxiliary  apparatus,  say  of 
i  pound  absolute,  the  temperature  of  the  exhaust  will  be 
102°  Fahr.  This  is  a  difference  of  110°  Fahr.  or  an  approxi- 
mate gain  of  33.5  B.T.U.  per  pound  of  steam;  since  an 
engine  which  exhausts  directly  into  the  atmosphere  has  a 
back  pressure  of  a  few  pounds  above  the  atmosphere,  due 
to  friction,  the  gain  may  be  even  greater  than  this.  In 
order  to  create  a  vacuum  into  which  to  discharge  the 
exhaust  steam,  a  condenser  is  applied  which  extracts  the 
latent  heat  from  the  steam. 

Vacuum    is    measured    in   inches  of  mercury,  30  inches 
being   assumed  as  a  perfect   vacuum.       This   value   varies 
according  to  atmospheric    conditions,  sometimes   being   as 
low  as  29  inches  and  again  as  high  as  31  inches.     It  will 
therefore    be    seen 
that  this  is  not  an 
accurate    means  of 
measurement.       A 
more    accurate 
system  of   measur- 
ing is  expressed  in 
percentage    of    the 
atmospheric  *  pres- 
sure.       With     this 
method  two  instru- 
ments are  required 
or   else   an    instru- 


FIG.  i.     Worthington  Jet  Condenser. 


ment  with    two   springs,    one   for   barometric   readings   and   the   other  for  vacuum 
reading  in  percentage. 

Classification.  —  Condensers  may  be  divided  into  two  main  classes,  viz.,  jet  and 
surface  condensers.  In  the  former  water  is  injected  directly  into  the  exhaust  steam, 
which  gives  this  apparatus  its  name,  jet  condenser.  The  surface  condenser  is  so  called 


CONDENSERS. 


241 


New  Condenser  Apparatus  at  the  74th  St.  Plant,  New  York.       (Original  Condenser  of  the 

motor  driven,  air  pump  type.) 


Surface  Condenser  Plant  (motor  driven)  Tramway  Power  Plant  at  Pinkston,  Glasgow. 


242 


STEAM-ELECTRIC   POWER   PLANTS. 


for  the  reason  that  the  condenser  water  is  used  to  cool  a  number  of  tubes,  the  exhaust 
steam  coming  in  contact  with  the  exterior  surface  of  these  tubes. 


w/////////M^^ 


FIG.  2.     Weiss  Counter-Current 
Dry  Jet  Condenser. 


The  surface  condenser  may  be  sub-classified  as  parallel  and  counter-current  flow 
types.  These  classifications  are  self-explanatory.  In  the  former  case  the  water  will 
flow  in  the  same  direction  as  the  steam,  and  vice  versa. 


CONDENSERS. 


243 


The  jet  condenser  may  be  sub-classified  as  "wet"  and  "dry."  The  former  is  so 
designed  that  the  air  and  vapor  are  discharged  with  the  condenser  water;  the  latter  is 
supplied  with  a  separate  so-called  dry  vacuum  pump  for  the  removal  of  air  and  vapor. 

The  wet  jet  condenser  may  be  applied  as  a  barometric  condenser,  or  have  its  dis- 
charge directly  connected  to  the  suction  of  a  combined  circulating  and  air  pump,  as 
shown  in  Fig.  i,  while  the  dry  type  is  exclusively  built  as  a  barometric  condenser  (Fig.  2). 

The  dry  jet  condenser  is  also  classified  as  parallel  and  counter  current;  if, 
for  instance,  the  flow  of  air  and  vapor  is  opposed  to  the  flow  of  water,  the  condenser 


FIG.  3.  Bulkley  Condenser  Supplied  from  a  Natural  "  Head  "  of  Water. 

is  of  the  counter- current  type,  and  vice  versa.  Another  application  of  the  barometric 
wet  jet  condenser  is  known  as  the  siphon  condenser,  Fig.  3.  This  design  is  very 
economical,  as  it  requires  no  moving  parts,  provided  that  a  natural  water  supply  is 
at  hand  of  not  less  than  15  feet  above  the  hot  well,  which  must  be  34  feet  below 
the  condenser  vessel.  After  once  being  started  this  condenser  is  entirely  automatic. 
With  any  greater  lift  the  operation  will  not  be  satisfactory  and  a  supply  pump  is 
required.  It  is  not  necessary  to  use  an  air  pump  with  this  type  of  condenser,  for 
the  condensation  takes  place  directly  above  a  contracted  neck,  wherein  is  produced 


244  STEAM-ELECTRIC   POWER  PLANTS. 

so  high  a  velocity  of  the  jet  that  the  air  and  vapor  are  carried  down  with  the  water 
into  the  hot  well. 

Application.  —  In  laying  out  a  power  plant  careful  consideration  should  be  given 
to  the  local  water  supply,  to  determine  whether  it  will  be  economical  to  install  con- 
densers. This  depends  also  on  the  size  of  the  plant,  type  of  machinery  and  price  of  coal. 

When  the  plant  is  so  located  that  it  is  difficult  to  obtain  water  other  than  from  the 
city  mains,  special  provision  for  re-cooling  the  discharge  may  be  applied.  A  condition 
similar  to  the  above  would  be  where  plant  was  located  on  a  small  canal,  from  which 
water  could  be  drawn  during  certain  hours  of  the  day  only.  In  cases  like  this  the 
water  would  be  collected  in  a  reservoir  and  re-cooled  by  means  of  a  cooling  tower. 

It  is  frequently  claimed  that  it  is  not  economical  to  install  a  condensing  apparatus 
in  small  plants.  This  depends  largely  on  the  type  of  prime  mover,  whether  turbine  or 
reciprocating  engine.  High  vacuum  with  a  turbine  is  essential  to  secure  economy, 
while  with  a  reciprocating  engine  the  benefit  of  high  vacuum  is  less.  Furthermore, 
the  percentage  of  steam  consumption  necessary  to  operate  the  condensing  apparatus 
in  a  small  plant  is  much  larger  per  unit  capacity  than  that  required  in  a  large  plant. 

Where  fuel  and  labor  are  cheap  the  saving  in  steam  produced  by  the  condenser 
may  not  save  enough  money  to  pay  a  sufficient  percentage  on  the  investment  or  first 
cost  of  the  apparatus. 

Condenser  Water  Required.  —  The  amount  of  water  required  to  thoroughly  con- 
dense the  steam  is  dependent  upon  two  conditions,  the  total  heat  and  weight  of  the 
steam,  and  the  temperature  of  the  injection  water. 

To  estimate  the  volume  of  water  for  condensing  purposes  under  any  specific  con- 
ditions, the  following  formula  will  be  of  assistance : 

Given:  /  =  Temperature  of  injection  water. 

D  =  Temperature  of  discharge  water. 

S  =  Total  heat  (sum  of  sensible  and  latent  heat)  of  the  steam  at 
the  pressure  at  which  it  leaves  the  engine. 

S  —  D 
Then:    j: j  =  Unit  weights  of  injection  water  required  per  unit  weight  of  steam. 

Example :  I  =  70°  Fahr. 

D  =  110°  Fahr.  with  a  vacuum  of  26  inches. 
5  =  1,190  units  of  heat. 

1,190  —  no 

Hence:  -  =27.0. 

no  —  70 

That  is,  the  weight  of  the  injection  water  required  will  be  27.0  times  the  weight  of 
the  steam  exhausted. 

Upon  a  test  with  no  air  leaks  it  might  be  possible  to  carry  the  discharge  water 
at  a  higher  temperature  than  no0,,  thus  reducing  the  quantity  of  condensing  water 


CONDENSERS. 


245 


FIG.  4.     Alberger  Barometric  Counter-Current  Condenser. 


246 


STEAM-ELECTRIC   POWER   PLANTS. 


required.  As  a  general  rule,  it  may  be  stated  that  a  temperature  of  discharge  water 
within  1 5°  of  the  temperature  corresponding  to  the  vacuum  in  the  condensing  chamber 
is  as  high  as  can  be  expected  in  actual  service.  The  difference  is  due  to  the  partial 
destruction  of  the  vacuum  by  the  air  present  in  the  condenser. 

Jet  Condenser.  —  The  accompanying  illustration,  Fig.  4,  represents  the  Alberger 
barometric  condenser,  which  is  of  the  counter-current  type.     It  will  be  noticed  that 


FIG.  5.     Two  Alberger  Condensers  Connected  to  One  Twin  Compound 
Engine.     (The  Engineer?) 

the  water  is  brought  into  the  vessel  on  the  right-hand  side,  and  passes  downward  over 
a  cone  so  arranged  that  it  divides  the  water  into  a  fine  spray,  which  comes  in  contact 
with  the  steam  entering  from  the  opposite  side.  The  air  and  vapor  rise  through  the 
hollow  cone  to  the  upper  part  of  the  vessel  into  an  air  cooler,  where  they  come  in  con- 


UNIVERSITY 


CONDENSERS. 


247 


tact  with  a  small  percentage  of  the  condensing  water,  thus  reducing  the  air  tempera- 
ture before  it  is  drawn  away  by  the  dry  vacuum  pump.     It  will  be  noticed  that  the 

spray  cone  is  suspended  on  a  spring,  so  that  if  the 
engine  is  running  under  a  light  load  and  a  small 
amount  of  water  is  passing  through  the  condenser,  it 
will  be  as  properly  sprayed  as  if  a  larger  amount  were 
passing  through,  which  would  compress  the  spring 
by  forcing  the  cone  downward,  increasing  the  escaping 
area.  This,  as  well  as  all  other  barometric  condensers, 
must  be  placed  not  less  than  34  feet  above  the  over- 
flow of  the  hot  well. 

Fig.  5  represents  an  Alberger  condenser  unit,  con- 
nected to  a  twin  compound  engine.  Nine  of  these 
were  installed  in  the  59th  Street  power  station,  New 
York  City.  Each  of  these  condensers  receives  the 
exhaust  from  one  low-pressure  cylinder,  and  as  both 
of  these  condensers  are  operated  from  a  single  dry 
vacuum  pump  and  a  single  circulating  pump,  it  is  of 
importance  to  maintain  equal  vacua  in  both  con- 
densing vessels.  It  will  be  noticed  that  the  air  pipes 


FIG.  5a.     Side  Elevation  of  Fig.  5.      (The  Engineer?) 


from   both   condensers   are   connected   to  one  suction   pipe;  this  also  pertains  to  the 
circulating  water  supply,  although  it  is  not  shown  in  this  cut.      An  equalizing  pipe 


248 


STEAM-ELECTRIC  POWER   PLANTS. 


connects  both  vessels,  still  further  assisting  in  establishing  an  equal  vacuum.     The 
side    elevation  of  this  same   installation  is  seen   in  Fig.  5a;  joined  directly  to  the 


Street  By  Jounuil 


FIG.  6. 


Condenser  Arrangement  with  a  6,ooo-K.W.  Turbine  at  the  Delaware  Ave.  Plant, 
Philadelphia.     Note  arrangement  of  the  Centrifugal  Pump. 


condenser  is  the  atmospheric  relief  valve,  to  discharge  the  exhaust  directly  to  the 
atmosphere  automatically  should  the  vacuum  be  broken. 

The  tail  pipe  of  a  barometric  condenser  must  be  submerged  in  the  hot  well  to  a 
sufficient  depth  so  that  the  amount  of  water  between  the  bottom  of  the  pipe  and  the 
overflow  will  not  be  less  than  i  \  times  the  amount  contained  in  the  tail  pipe. 

Surface  Condenser.  —  The  surface  condenser  consists  of  a  large  number  of  brass 
tubes  usually  f  or  i  inch  in  diameter,  and  interconnected  at  their  ends  by  so-called 
head  plates,  in  which  the  tubes  are  packed  and  kept  tight  by  a  stuffing  box  and  screw 
gland.  The  circulating  or  cooling  water  passes  through  these  tubes  at  a  velocity  of 
from  350  to  500  feet  per  minute,  while  the  steam  passes  around  them,  being  confined 
by  the  enclosing  shell  of  the  condenser,  which  is  generally  made  of  cast  iron,  while  in 
Europe  wrought  iron  shells  are  frequently  employed  with  large  size  condensers. 

The  condenser  is  rated  by  the  condensing  surface  contained  in  the  tubes,  and 
under  ordinary  conditions  3.75  to  4  square  feet  are  allowed  per  kilowatt  of  turbine 
capacity.  This  latter  figure  may,  however,  be  increased  in  tropical  climate,  where  the 
temperature  of  the  cooling  water  is  high. 

With  the  steam  turbine  it  pays  to  install  condensers  large  enough  to  create  high 
vacua,  for  the  efficiency  of  the  turbine  depends  largely  on  the  exhaust  pressure.  In 
order  to  assist  in  obtaining  a  high  vacuum  with  a  comparatively  small  condenser, 
Parsons,  the  inventor  of  the  turbine  of  that  name,  designed  a  vacuum  augmenter.  It 


CONDENSERS. 


249 


consists  practically  of  a  steam  injector,  as  will  be  seen  in  Fig.  7,  located  in  the  suction 
pipe  to  the  air  pump.    This,  of  course,  adds  to  the  steam  consumption,  and  it  is  claimed 

i 


.„ Main 

Condenjer         ~"  ~— 


FIG.  7.     Arrangement  of  Parsons  Vacuum  Augmenter. 

that  this  addition  amounts  to  i  per  cent  of  that  of  the  turbine;  the  heat  of  this  steam, 
however,  is  not  entirely  lost,  for  it  raises  the  temperature  of  the  hot  well  water  and  con- 


LBS.    LBS 
50,000.    50 

25,000.  £5 

20,000.  '20 

1 

gj  5,000.    15 

4- 

3  10000.   10 
|2 

5.000.     5 
0.     0( 

^ 

X 

^ 

I/ 

i 

*%: 

''%t/of 

Jg 

2 

^>° 

% 

^ 

^ 

A 

x 

^ 

*:t!°ur 

^ 

K.hfs. 

-—      — 

'^X 

^ 

1 

X 

-^ 

—  «-.. 

—  . 



•0- 

I 

X^ 

•< 

^ 

SH 
)OK.V 

EFFI 
.     Z 

2LD 
•HAS 

CORP 

:  ALT 

)RAT 
.  200 

ON. 
3  VOL 

rs. 

8. 

<2 

^ 

Me 

in  Sbc 

pValv 
Mea 

'.  Pres 
nSupe 

jure 
rheat 

33  LBS 

ihren 

ive  At 

eiC. 

mosphf 

re. 

| 

1 

x 

* 

WiCh 

Mec 
Vacuu 

nSpe 

m  Aug 

d   1,50 
mentc 

3  Revs, 
r  thus 

per  Mi 



X 

s' 

•*— 

~~^L 

--_.. 

— 

— 

LVdcy 

wm_Lin 

e.JJa. 

wriete 

r.so: 

..i 

Vr£L 

~  —  -^. 

•*•      -. 

—  S 

icuun 

T— 

_£jefc 

l£i3C 

;  . 

•*-  — 

)         100      200      500     400      500     600      700      800      900      1,000     1,100     1,200     1,500     1400     l£00     1,600    .1,700     1,800  Kito-wattS 
Load  on  Machine  in  Kilo-  watts.               FuHLoad. 

FIG.  8.     Effect  of  Parsons  Vacuum  Augmenter. 

sequently  that  of  the  boiler  feed,  provided  that  the  water  is  not  allowed  to  lie  in  the 
hot  well  long  enough  to  radiate  this  heat.    Fig.  8  *  shows  the  effect  of  a  Parsons  aug- 


*  "Journal  of  the  Institution  of  Electrical  Engineers." 


250 


STEAM-ELECTRIC   POWER    PLANTS. 


menter  as  installed  in  conjunction  with  a  i,5oo-K.W.  turbine,  in  the  Sheffield  Corpora- 
tion power  plant,  the  amount  of  steam  consumed  by  the  augmenter  is  included  in  the 
total  steam  consumption  of  the  turbine. 

As  previously  stated,  the  large  number  of  turbines  which  have  been  installed  has 
greatly  increased  the  use  of  surface  condensers.     The  reason  for  this  is  that  the  exhaust 


FIG.  9.     Arrangement  of  Baker  Oil  Separator  and  Wheeler  Surface  Condenser  Mounted 
upon  Combined  Air  and  Circulating  Pumps. 

steam  of  the  turbine  contains  no  oil,  and  therefore  the  water  of  condensation  may  be 
returned  to  the  boilers,  instead  of  being  wasted,  as  is  the  case  with  reciprocating  engines, 
unless  some  apparatus  to  remove  the  oil  from  the  exhaust  steam  or  from  the  hot  well 
water  is  applied.  A  device  of  this  kind,  and  its  pipe  connections,  is  shown  in  Fig.  9. 
It  will  be  seen  that  the  oil  separator  is  placed  between  the  engine  exhaust  and  the  con- 
denser inlet.  The  oil  is  removed  from  the  steam  in  the  separator  and  flows  by  gravity 
into  the  receiver  tank,  whence  it  is  removed  when  the  tank  fills.  This  cut  also  shows 
the  location  of  the  atmospheric  relief  valve.  The  gate  valve  shown  between  the  relief 
valve  and  the  oil  separator  is  for  cutting  out  the  condenser  in  case  of  repairs. 

A  cross-section  of  this  particular  condenser,  which  is  of  the  Wheeler  type,  is 
shown  in  Fig.  10.  In  this  cut  the  condenser  is  mounted  on  a  combined  air  and  cir- 
culating pump,  and  is  of  the  counter-current  type;  the  circulating  water  entering,  as 
shown,  at  the  lower  right-hand  corner,  travels  in  an  opposite  direction  from  the  steam 
entering  at  the  top,  so  that  the  hottest  steam  comes  in  contact  with  the  hottest  water  and 
vice  versa.  The  air  pump  handles  all  the  condensed  steam  as  well  as  the  air  and 
uncondensed  vapor  discharging  into  the  hot  well  tank,  from  which  the  boiler  feed  may 
be  taken.  When  it  is  desirable  to  use  the  circulating  water  over  again,  the  discharge 
of  the  circulating  pump  may  be  piped  to  a  cooling  pond  or  tower.  This  subject  will 
be  treated  in  a  succeeding  article. 


CONDENSERS. 


251 


Plants  equipped  with  the  Curtis  turbine  are  frequently  provided  with  a  so-called 
"base  condenser."  In  this  case  the  turbine  is  mounted  directly  upon  the  condenser. 
This  forms  a  very  compact  apparatus,  requiring  much  less  floor  space  than  a  separate 
condenser,  and  is  therefore  used  to  a  considerable  extent.  Its  disadvantage  is  that 
the  condenser  cannot  be  repaired  without  shutting  down  the  turbine.  This  type,  as 
well  as  all  others,  should  be  provided  with  an  atmospheric  relief  valve;  if,  however, 
anything  happens  to  the  base  condenser,  so  that  the  turbine  discharges  to  the  atmos- 


FIG.  10.      Surface  Condenser  Mounted  on  Combined  Air  and  Circulating  Pump  of  the 
Wheeler  Condenser  and  Engineering  Co. 

phere,  the  circulating  pump  should  continue  in  operation  to  prevent  the  packing 
around  the  tubes  from  being  burned  out.  If  this  packing  is  injured  the  condenser 
will  leak  and  the  vacuum  be  destroyed. 

When  the  exhaust  from  auxiliary  machinery  is  not  enough  to  raise  the  temperature 
of  the  boiler  feed  water  to  a  sufficiently  high  degree,  or  where  motor-driven  auxiliaries 
are  used,  the  upper  row  of  tubes  near  the  steam  inlet  may  be  so  arranged  that  the  dis- 
charge of  the  boiler  feed  pump  will  pass  through  them,  thus  utilizing  the  condenser 
as  an  auxiliary  feed  water  heater.  A  similar  arrangement  of  heater  in  the  engine 
exhaust  is  shown  in  Fig.  3. 

Fig.  ii  represents  a  complete  condensing  unit  of  the  Worthington  pattern.  It 
will  be  noticed  that  in  this  type  of  apparatus  there  are  three  separately  driven  pumps, 
viz.,  circulating  pump,  dry  vacuum  pump  and  hot  well  pump.  The  two  former  are 


2$2  STEAM-ELECTRIC   POWER   PLANTS. 

steam  driven,  while  the  latter  is  motor  driven.  It  is  frequently  claimed  that  auxiliary 
machinery  can  be  more  economically  driven  by  steam  than  by  electricity,  and  that  the 
liability  of  break-down  is  increased  in  the  latter  case.  It  is  the  author's  opinion  that 
the  above  condenser  layout  would  be  more  systematic  if  all  of  the  pumps  were  steam 
driven  or  vice  versa. 

Care  should  be  taken  that  the  hot  well  pump  be  located  at  least  three  or  four  feet 
below  the  hot  well.  This  precaution  should  be  taken  in  order  to  secure  a  hydrostatic 
head  to  the  suction  of  the  pump,  so  that  the  hot  water  will  fall  in  a  solid  body,  thereby 
overcoming  to  some  extent  the  high  vacuum  which  is  on  the  top  of  the  hot  well  and 
securing  a  constant  flow  to  the  pump  suction. 

The  best  practice  is  to  provide  the  surface  condensing  plant  with  separately  driven 
circulating  pump,  dry  vacuum  pump  and  hot  well  pump.  These  pumps  should  be 
grouped  around  their  prime  mover  in  order  to  form  a  complete  unit  system,  so  as  to 
facilitate  easy  operation.  Modern  power  plants  are  always  equipped  with  one  or  two 
prime  movers  in  reserve,  and  should  any  pump  require  repairs  the  complete  unit  will 
be  shut  down  and  one  of  the  reserve  units  cut  in. 

Central  Condenser.  —  Frequently  two  or  more  prime  movers  are  connected  to  a 
common  condenser,  called  a  central  condenser.  This  practice  usually  results  in  long 
exhaust  mains.  Care  must  be  taken  that  a  condenser  of  this  character  be  placed  as 
near  the  exhaust  ports  as  possible,  in  order  to  minimize  leakage  at  joints  and  friction. 
All  engine  connections  should  be  properly  valved  or  the  leakage  will  be  considerably 
increased  through  the  engine  stuffing  boxes  when  the  engine  is  shut  down.  Some 
barometric  condensers  are  especially  adapted  to  withstand  large  variations  in  load;  a 
type  of  this  class  is  shown  on  Fig.  2,  representing  the  Weiss  counter-current  system. 

The  central  condensing  system,  be  it  either  surface  or  jet  condenser  type,  may  con- 
trol the  entire  plant,  provided  the  plant  is  not  too  large,  in  which  case  three  or  four 
prime  movers  may  be  grouped  on  one  central  condensing  system.  This  latter  scheme 
has  been  used  in  the  Kingsbridge  plant  in  New  York. 

Where  a  single  central  condensing  system  is  used  in  a  plant  of  large  capacity,  it  is 
advisable  to  install  emergency  pumps,  so  that  if  one  or  more  of  the  pumps  break  down 
it  will  not  be  necessary  for  the  engines  to  exhaust  into  the  atmosphere.  The  efficiency 
of  the  central  condensing  system  is  higher  than  that  of  the  unit  condensing  system, 
because  the  large  units  employed  operate  on  a  smaller  steam  consumption;  it  also 
needs  less  attention. 

Vacuum  Breaker.  — A  vacuum  breaker  should  be  installed  in  the  piping  of  the 
vacuum  pump,  as  a  means  of  safety.  If  any  accident  should  happen  to  the  wiring 
system,  or  if  for  any  reason  the  load  should  be  cut  off,  the  engine  would  be  liable  to  run 
away  with  a  large  vacuum  on  the  exhaust.  The  arrangement  for  breaking  the  vacuum 
is  very  simple :  a  small  pipe  is  connected  to  the  vacuum  pump  suction  pipe,  to  which 
is  attached  a  valve,  provided  with  a  screen,  admitting  atmospheric  pressure  to  the 
condenser. 


CONDENSERS. 


253 


C 

o 
U 

d 

o 

0 


254 


STEAM-ELECTRIC  POWER   PLANTS. 


Cooling  Towers.  —The  location  of  power  plants  often  limits  the  amount  of  con- 
denser water  that  may  be  obtained.  One  is  therefore  forced,  when  the  plant  is  run 
condensing,  to  cool  the  condenser  water,  and  use  it  over  and  over  again.  This  can 
be  done  either  by  a  cooling  tower  or  a  pond;  the  latter  will  be  described  under  separate 
heading. 

Cooling  towers  are  either  wooden,  as  commonly  used  in  Europe,  or  of  steel  as  is 
the  practice  in  America.  A  more  recent  method  is  to  build  them  of  reinforced  con- 
crete. This,  however,  has  not  been  done  to  any  considerable  extent. 

Cooling  towers  may  be  classified  as  natural  draft  and  forced  draft.  The 
latter  are  equipped  with  one  or  more  fans.  This  type  is  generally  used  in  America, 


FIG.  12.     Typical  German  Cooling  Tower. 

and  is  preferable  where  ground  space  is  limited.  Its  height  is  also  less  than  that  of 
the  natural  draft  type.  The  steel  forced-draft  tower  requires  a  ground  area  of 
from  i.i  to  1.3  square  feet  per  100  pounds  of  steam  condensed;  the  wooden  forced 
draft-tower  requires  from  1.3  to  3  square  feet  for  the  same  amount  of  exhaust  steam. 
This  large  difference  is  due  to  the  difference  in  design  and  the  cooling  effect  of  the 
iron.  The  natural-draft  cooling  towers  are  generally  built  of  wood  and  have  a 
height  of  from  40  to  75  feet.  The  area  required  for  these  towers  amounts  to 


CONDENSERS. 


255 


from  6  to  8.5  square  feet  per  100  pounds  of  exhaust  steam.  These  figures  are  based 
on  practical  experience  and  average  working  conditions.  The  circulating  water  is 
taken  at  a  temperature  of  from  60°  to  65°  Fahr.  and  the  amount  of  cooling  water  per 
pound  of  steam  condensed  is  from  30  to  35  pounds  with  an  atmospheric  temperature 
of  from  50°  to  65°  Fahr.  and  an  average  humidity. 

From  the  above  it  may  readily  be  observed  that  the  size  of  the  cooling  tower  depends 
on  many  existing  conditions,  such  as  the  amount  of  steam  to  be  condensed,  the  amount 


FIG.  13.     Architectural  Design  of  Cooling  Towers. 

and  temperature  of  condenser  water,  the  temperature  and  humidity  of  the  atmosphere 
and  the  difference  in  temperature  of  the  circulating  water  created  by  the  cooling  tower. 


256 


STEAM-ELECTRIC  POWER  PLANTS. 


In  order  to  avoid  the  pumping  of  the  condenser  water  over  the  cooling  trays  in 
the  cooling  tower,  the  discharge  of  the  condenser  must  flow  by  gravity  above  the  trays. 
This  may  mean  in  some  cases  that  the  cooling  tower  must  be  sunk  below  grade  level, 
an  example  of  which  is  shown  in  Fig.  12.  This  type  of  the  tower  itself  is  typical  of 
Continental  practice.  It  is  of  cheap  construction,  being  made  entirely  of  wood,  and 
is  very  bulky  in  appearance  and  seldom  if  ever  in  harmony  with  the  architectural 


^^^ff^^^^^p^pfej^'^^^^^^. 


NATURAL  DRAFT  II 
COOLING  TOWER 


COLD  WELL 


FIG.  1  4.     Alberger  Barometric  Condenser  and  Natural-Draft  Cooling  Tower. 


design  of  the  plant  building.  It  is  possible,  however,  to  give  an  artistic  finish  to  the 
tower,  as  will  be  seen  in  the  accompanying  illustration,  Fig.  13.  These  towers  were 
designed  by  H.  Friederichs  &  Co.,  Logan,  Germany.  In  any  case  the  water  must 
be  pumped  before  or  after  cooling. 

A  typical  American  layout  for  condenser  and  cooling  tower  is  shown  in  Fig.  14. 
This  illustration  represents  an  Alberger  condensing  plant.  The  figure  is  clear  and 
self-explanatory.  Fig.  15  is  a  cross-section  of  the  Worthington  forced-draft  cooling 
tower;  it  will  be  seen  that  the  condenser  discharge  enters  near  the  bottom  of  the  tower 


CONDENSERS. 


257 


and  is  pumped  up  through  a  standpipe  to  a  distributer.  This  distributer  consists  of 
a  number  of  arms,  constructed  of  perforated  pipes ;  these  perforations  are  all  on  one 
side,  and  the  velocity  of  the  water  discharging  through  these  holes  causes  the  dis- 
tributer to  revolve.  The  entire  cross- sectional  area  of  the  tower  is  filled  with  a  large 


TOWER 


X    <«  HOT  WATEft, 


COLO  WATER. 


FIG.  15.     Worthington  Forced-Draft  Cooling  Tower. 


number  of  tubes  made  of  thin  wrought  iron,  and  arranged  in  sections;  these 
sections  are  staggered.  The  water  discharged  from  the  distributer  runs  over  these 
tubes  and  is  equally  distributed,  giving  off  its  heat  to  the  metal  and  also  to  the 
air  passing  upward. 

A  similar  cooling  device  to  the  cooling  tower  is  the  so-called  open  cooler.     It  con- 
sists usually  of  a  wooden  structure  upon  which  a  number  of  laths  are  arranged  in  stag- 


258 


STEAM-ELECTRIC   POWER   PLANTS. 


gered  rows;  the  water  flowing  from  row  to  row  is  split  up  into  thin  sheets  and  cooled 
by  the  surrounding  air.  A  good  example  of  this  type  of  open  cooler,  combined  with  a 
barometric  condenser,  is  shown  in  Fig.  16.  The  condenser  employed  is  of  the  dry  jet 
counter-current  type  and  a  special  air  cooler  is  provided  outside  the  condenser  vessel. 
It  will  be  noticed  that  after  the  water  passes  through  the  condenser  it  is  pumped  up  to 
the  top  of  the  cooler,  which  is  upon  structural  steel  work.  In  order  to  give  it  sufficient 


FIG.  1 6.     Arrangement  of  Condenser  and  Open  Cooling  Plant  as  installed  by  the  Mirrlees 

Watson  Co.,  Glasgow. 


air  supply  they  are  frequently  located  on  the  roof  of  the  buildings.  The  condenser 
itself  does  not  require  any  supply  pump,  as  the  water  cooler  collecting  tank  is  so  close 
to  the  condenser  vessel  that  the  condensing  water  will  siphon. 

Cooling  Ponds.  — A  simpler  and  cheaper  method  of  cooling  condensing  water  is  to 
install  cooling  ponds.  These  ponds  are  nothing  more  than  a  lake,  above  which  are 
arranged  a  series  of  pipes  provided  with  spray  nozzles.  The  water  at  about  fifteen 


CONDENSERS. 


259 


RELATION  OP  NOZZLE  TEMPERATURE  TO  AIR  AND  COOLINQ  POND,  SEPTEMBER,  19041 
FIG.  17. 


q 

$ 

"1 

s 

s 

e- 

/ 

\ 

§SI 

A 

x^ 

/ 

\ 

^ 

•^. 

\ 

/ 

/ 

\ 

/ 

/ 

/ 

E  ss 

n- 

\ 

/ 

s 

/ 

\ 

/ 

/ 

s, 

El 

A^ 

/ 

/ 

\ 

fc  u 

S 

^ 

X" 

\ 

/ 

\ 

, 

/ 

\ 

"^~f 

lu   5 

\ 

/ 

\ 

~. 

\ 

/ 

\ 

/ 

\ 

/ 

•^ 

9 

S 

' 

/ 

s 

/ 

\ 

/ 

^ 

14 

2 

\ 

f 

^ 

V 

\ 

I 

\ 

S  Jt 

in 

t 

/ 

\ 

/ 

\ 

^—  • 

•—  - 

j> 

t 

\ 

I 

\ 

/ 

/ 

\ 

k  J, 

C 

1 

\ 

/ 

\ 

/ 

\ 

s 

xl 

T* 

<t 

~^ 

' 

^ 

/ 

\ 

1 

>Jr 

^ 

\ 

/ 

\ 

1 

^ 

\ 

/ 

^ 

K 

\ 

/ 

15 

n 

s 

r-i 

(7 

— 

TV 

— 

n 

'C 

"f 

t 

;  , 

- 

' 

9 

( 

t 

,1 

(• 

r 

f 

71 

f 

y  i 

a  i 

n 

i 

31 

1-1 

f' 

<•' 

7- 

/, 

frf 

<>„ 

/ 

RELATION  OF  NOZZLE  TEMPERATURE  TO  AIR  AND  COOLING  POND,  JANUARY,  1905. 


FIG.  i 8. 


260 


STEAM-ELECTRIC   POWER   PLANTS. 


> 

w 

G 
rt 


PH 
bo 
.S 

8 

u 


CONDENSERS. 


26l 


pounds  pressure  issuing  from  the  nozzle  is  torn 
into  spray,  and  in  this  form  projected  through  the 
air.  Under  favorable  atmospheric  conditions  of 
humidity  the  water  may  be  cooled  several  degrees 
below  the  atmospheric  temperature,  but  at  all  times 
to  a  temperature  sufficiently  low  for  effective  conden- 
sation. 

These  cooling  ponds,  like  cooling  towers,  operate 
more  efficiently  during  cold  weather  than  during  warm 
weather,  as  will  be  seen  in  the  accompanying  charts, 
Figs.  17  and  18,  the  readings  of  which  have  been  taken 
from  the  Chattanooga  Electric  Company's  plant,  and 
show  the  difference  between  the  temperature  of  a 
summer  month  and  those  of  a  winter  month.  During 
the  month  of  September  the  condensing  water  was 
cooled  about  12°  Fahr.,  while  in  January  the  difference 
in  temperature  was  18°  Fahr.  During  the  time  that 
the  records,  as  shown  on  the  charts,  were  taken, 
a  vacuum  of  from  27  inches  to  28  inches  was  main- 
tained. 

Usually  these  ponds  are  located  on  the  ground, 
but  they  are  occasionally  placed  on  the  roof.  In  the 
former  case  the  water  may  flow  by  gravity,  provided 
the  condenser  is  located  high  enough  to  produce 
sufficient  hydrostatic  head;  in  the  latter  case,  which 
may  be  chosen  where  ground  space  is  limited,  an 
additional  supply  pump  is  necessary.  A  scheme  of 
this  type  is  illustrated  in  Fig.  19.  The  system  shown 
is  of  the  Schutte  &  Koerting  Company's  design.  The 
steam,  after  leaving  the  engine,  is  condensed  in  a 
Schutte  &  Koerting  eductor  condenser  (see  Fig.  20). 
The  water  is  collected  in  a  hot  well  trench  from 
which  it  is  lifted  by  means  of  a  centrifugal  pump  to 
the  roof,  where  it  is  discharged  through  the  spray 
nozzles.  The  cooled  water  is  collected  at  the  eaves 
in  gutters,  and  drains  back  to  the  water  inlet  of  the 
condenser,  thus  completing  the  circuit.  In  order  to 

keep  the  wind  from  blowing  the  finely  divided  particles  of  water  upon  surrounding 
property,  a  wooden  fence  is  erected  on  top  of  the  building  walls,  consisting  of 
timbers  and  laths. 


FIG.  20.    Schutte  and  Koert- 
ing Eductor  Condenser. 


262 


STEAM-ELECTRIC   POWER   PLANTS. 


PUMPING   MACHINERY. 

Steam  or  Electric  Drive.  — The  pumping  machinery,  as  well  as  all  other  auxiliary 
machinery,  may  either  be  steam  or  electrically  driven.  If  steam  driven,  the  exhaust 
steam  may  be  used  for  heating  the  feed  water  which  under  favorable  conditions,  and 
utilizing  the  exhaust  from  the  exciter  and  blowrer  engines,  etc.,  may  be  raised  to  200° 
Fahr.  The  entire  amount  of  steam  used  in  the  auxiliaries  will  be  from  5  per  cent  to 


FIG.  i.     Motor-Driven  Surface  Condenser  Plant  as  Manufactured  by  the  Mirrlees  Watson 

Co.,  Glasgow. 


10  per  cent,  occasionally  running  as  high  as  15  per  cent  of  the  total  steam  consump- 
tion, in  which  case  it  may  be  possible  to  heat  the  feed  water  to  200°  Fahr. 

Where,  however,  electrically  driven  pumping  machinery  is  installed,  there  is  no 
exhaust  for  heating  the  feed  water,  in  which  case  the  water  should  be  heated  either  by 
economizers  or  live  steam.  It  is  essential  to  install  a  storage  battery,  so  as  to  guard 
against  break-down;  this,  anyhow,  is  necessary  for  high-voltage  plants  for  operating 
the  oil  switches.  It  is  also  a  good  practice  to  float  a  storage  battery  on  the  exciter 
current.  From  the  foregoing  it  will  be  seen  that  the  installment  of  a  storage  battery 
is  practically  essential  without  the  employment  of  electric-driven  auxiliaries.  The 
claim  frequently  made  that  a  break-down  of  the  main  bus-bars  would  also  stagnate  the 
auxiliaries  is  not  justified,  for  the  reasons  mentioned  above.  The  installation  of  motor- 


PUMPING  MACHINERY.  263 

driven  auxiliaries  is  neater,  cleaner,  easier  to  operate,  and  does  not  require  so  much 
floor  space  as  steam  driven.  Should  a  break  occur  to  the  feeder  to  any  pump,  the 
repairs  may  be  made  in  a  shorter  time  than  in  case  of  a  rupture  in  the  steam  pipe  sup- 
plying a  steam  pump. 

In  favor  of  steam-driven  auxiliaries  it  is  said  that  practically  the  entire  heat  of  the 
steam,  excepting  of  course  that  which  is  transformed  into  mechanical  energy  and 
condensed  in  the  pipes,  will  be  sent  back  to  the  boilers  in  the  feed  water.  It  must, 
however,  be  remembered  that  all  auxiliary  machines  are  large  steam  consumers;  a 
boiler  feed  pump  will  consume  seventy-five  pounds  or  even  more  of  steam  per  horse- 
power hour,  if  driven  by  motor  a  horse-power  hour  may  be  obtained  from  the  bus-bars 
from  10  to  15  pounds,  depending  of  course  on  the  make  of  the  prime  mover.  As  a 
matter  of  fact  the  question  of  whether  to  employ  steam  or  motor-driven  machinery  still 
remains  a  matter  of  opinion.  On  the  Continent  of  Europe  motor-driven  auxiliaries 
are  almost  exclusively  used;  the  reverse  is  true  in  American  practice.  In  recent  instal- 
lations in  Great  Britain  many  of  the  plants  are  motor  driven.  In  order  to  avoid  two 
separate  steam-pipe  systems,  reducing  valves,  etc.,  it  is  of  prime  importance  to  install 
pumps  capable  of  withstanding  high  pressure  and  superheated  steam  as  used  by  the 
main  engines. 

Steam  Consumption  of  Auxiliaries. — The  steam  necessary  to  operate  the  various 
pumps  and  auxiliary  engines  depends  on  the  main  engines,  upon  the  condenser  equip- 
ment, and  the  vacuum  to  be  maintained.  The  average  steam  consumption  per  I.H.P. 
hour  of  the  various  pumps,  both  piston  and  plunger,  may  be  assumed  as  50 
pounds.  In  case  motor-driven  machinery  is  used,  the  current  being  taken  from  the 
bus-bars,  which  are  supplied  by  the  main  generator  unit,  where  an  indicated  horse- 
power hour  may  be  furnished  by  13  pounds  of  steam,  assuming  that  the  efficiency  of 
the  motor,  transformer,  etc.,  is  80  per  cent,  the  equivalent  steam  consumption  will  be 
15.6  pounds.  It  must,  however,  be  remembered  that  the  exhaust  from  a  steam-driven 
pump  may  be  utilized  in  the  feed-water  heater. 

The  average  steam  consumption  of  the  various  pumps,  as  compared  with  that  used 
in  the  main  engine,  may  be  considered  as  follows: 

Circulating  Pumps 1.5  per  cent 

Air  Pumps 0.8  "       " 

Hot  Well  Pumps 0.3  " 

Boiler  Feed  Pumps 1.5  " 

House  Pumps      0.4  " 

Oil  Pumps 0.6  " 

Exciters 0.5  " 

There  is  other  auxiliary  machinery,  such  as  is  necessary  for  the  operation  of 
mechanical  stokers,  coal  conveyors,  etc.  It  may  be  assumed  that  the  above  figures 
are  safe  for  up-to-date  installations. 


264 


STEAM-ELECTRIC   POWER   PLANTS. 


The  Steam  Turbine  Committee  of  the  Electric  Light  Association,  1905,  on  a  test 
of  the  auxiliaries  of  a  5,ooo-K.W.  Curtis  turbine  give  the  following  figures: 


A. 

B. 

Output  K  \V.             

3.410 

29-95 

28.7 

4,758 
29.96 
28.6 

Barometer           

HORSK-  POWER. 

69.1 
23.2 
9.2 
23-7 
5-8 
7-4 

69.1 
23.8 
9.8 

27.4 
5-6 

5-7 

Hot  Well  Pump         

Oil  Pump                                        

To  compare  the  power  required  in  percentage  of  the  auxiliaries  to  that  required  by 
the  main  engines,  2.9  per  cent  was  the  amount  in  "A"  and  2.1  per  cent  in  "B."  This 
percentage  will  decrease  as  the  turbine  reaches  normal  load  (5,ooo-K.W.),  and  thence 
on  will  increase. 

A  very  interesting  test  on  the  power  and  steam  required  by  the  auxiliary  plant  of 
a  400-K.W.  Parsons  turbine  in  the  Broad  Street  plant  of  the  Citizens'  Light  and  Power 
Company,  Johnstown,  Pa.,  was  reported  by  G.  R.  Bibbins  in  Power.*  The  turbine 
discharges  into  a  Weiss  dry-jet  counter- current  barometric  condenser.  The  con- 
denser is  designed  to  handle  24,000  pounds  of  steam  per  hour  with  injection  water  at 
70°  Fahr.,  and  with  a  barometric  reading  of  30  inches  capable  of  producing  a  vacuum 
of  27  inches.  It  will  be  seen  that  the  condenser  is  very  large  and  would  take  care  of 
three  turbines  similar  to  the  one  tested.  There  are,  however,  only  two  installed  at 
present.  The  chart  of  the  test  shown  in  Fig.  i  is  self-explanatory. 

Circulating  Pumps.  —  For  supplying  water  to  the  condenser,  either  a  centrifugal  or 
reciprocating  pump  may  be  employed.  The  former  is  more  generally  used,  as  its 
efficiency  is  much  higher.  The  centrifugal  pumps  used  are  exclusively  of  the  single 
stage  type,  as  they  are  not  required  to  pump  against  any  very  high  head;  they  are  either 
electrically  or  steam  driven.  They  are  designed  either  of  the  single  or  double  suction 
type.  The  single  suction  type  requires  a  thrust  bearing  which  is  eliminated  in  the 
double  suction,  owing  to  the  fact  that  the  water  coming  in  on  each  side  of  the  impeller 
equalizes  the  stress,  therefore  the  efficiency  of  the  double  suction  type  is  higher  than 
that  of  the  single  suction. 

For  determining  the  size  of  the  pump  the  most  unfavorable  conditions  should  be 
taken  into  consideration.  It  must  also  be  remembered  that  practically  all  railroad 

*  Power  required  for  condensing  auxiliaries  in  a  steam  turbine  plant.     (February,  1005.) 


PUMPING  MACHINERY. 


265 


•drand  J9)«M  oj  l<n<n  jo  -jaw  »  j 

• 

o 

S 

S 

CT* 

0 

S 

» 

g 

•j»pnit£j  are  joj  ppi  jo  jaw  j»j 

- 

« 

<c 

« 

5 

5 

o» 

O3 

O 

M» 

*2 

» 

•saijvn!*"*  joj 

p&imbaj  J»*od  pr}O)  jo  -jaao  jsj 

» 

CS 

S 

S 

fl 

CO 

c 

CO 

t- 

§ 

oi 

t- 

-* 

•damd  »,«M  oj. 

5' 

i 

t- 

^J 

c^ 

t£ 

01 

o 

If 

-T* 

5 

-*• 

a> 

u- 

japmi&>  ap"  jo  '<!  "H  'I 

~. 

3 

0 

c 

to 
« 

5 

CO 

S 

CO 

^' 

o 

£ 

•j»pmi£>  tum«  jo  -J  'H  'I 

L 

o 
fj 

t- 
t^ 

t^ 

e< 

rj 
01 

CD 

=0 

t- 
o^ 

t— 

-^ 

•duind  pa*  'Sns  jo  -J(  'd  11 

P 

5 

S 

51 

3 

•* 

O 

cr 

«* 

S 

•-o 

•oopnoD  JOJ  pdumbaj  nir^is  ;o  g 

>* 

3 

n 

3 

o 

CO 

- 

• 

-f 

41 

rt| 

tnTOW  'll  «<)  JSIISM  Sai|00*   sqi 

r- 

S 

!1 

CD 
CO 

CO 

i 

•O 

8 

•AiaajMMiu  £ioi|ixm 

'      0]  ajqwSjiiip    -uiui   jed    -sql 

5 

2 

« 

s 

^ 

o> 

2 

v 

o 

ro' 

•JAIlMJja   Hi 

'jojTriq  Qi  pazijtin  'ouu  Jdd  'sqi 

j 

S 

S 

0 

* 

9 

S 

t— 

|     •jConainsgs  piuiaaqi  fg  'jwnq 

£       01      p3JS.M|3p       UtIU     J»d      'tqq 

5 

-^ 

00 
h- 

-s- 

<—  . 

<0 

• 

C-) 

'C 

SI 

5 

ri 

c 

I 

_^                 -pasaapaoo  ainuuu  J3J 

5 

t* 

S 

r 

»ft* 

•i)' 

S 

L" 

p 

E 

sj            -pBOlnsst—  jncq    <£  'H  "d 

i 

0 

= 

0 

J 

0 

5 

O 

i 

< 

C-l 

,, 

_, 

J 

^« 

a 

•spjiu  raojj  '.moil  -j  'H  «<I 

CO 

« 

" 

.^ 

t" 
99 

s 

•jnoii  -j  -H  '3  J»d 

£ 

M 

r-H 

a 

* 

a 

3 

C) 

.•* 

j? 

^t 

H 

Ci 

Of) 

CO 

~T> 

« 

o 

•jnot|  -«n  MJ 

3 

S 

S 

S 

S 

s 

E2 

2 

•«;tp  uioj;  atnuiiu  j»j 

I 

r- 

* 

*^ 

0 

u 

'-; 

o 

i 

tt 
O> 

S 

•diund  .MJITM  pur  3oi 
)|*q  'dumd  JIB  jo  .(JU»IDU;»  -tp»K 

• 

-r 

S 

-3 

S 

2 

!£> 

EC  co 

s 

•J  'H  J»)»AV 

a. 

2 

09 
-P 

5 

it 

2 

t- 

A 

r. 

dmnd  1Snre»B—  p«q  r»)Ol 

£ 

00 

00 

(0 

S 

S 

00 

3 

S 

CO 

» 

•^Dnjraajs  ojj}9nin|0j\ 

^». 

5 

^> 

rp 

S 

S 

«o 

«) 

« 

»g 

S 

c 

•lnstujOMldsip  duinj 

o 

2 

CO 

-* 

^f 

0 

I 

S 

0 

1- 

o 
o 

•* 

§ 

o 

•psdrand  . 
.<H»nio»  ajnaim  jad  J»)WA\. 

3 

£ 

o 

i 

"•»« 

ro 

S 

S 

o 

5 

S 

•oai   'jtaM  J3AO   'aim  jad  J»)V^v 

•5 

o 

1 

r 

5 

S 

*» 

CO 
CO 

I 

00 

S 

•»P!«  .,t«  JJ»»—  aniproj  J»jn 

d 

^ 

"*". 

5 

00 

o> 

irt 

CO 
(N 

O 

« 

• 

•JMoapaoo  aioj;  jiy' 

i. 

CO 

s? 

£ 

-*< 

00 

5 

1 

•ni«»)s  )cn«t|x3 

ki 

« 

o 

O 

i 

• 

S 

5 

= 
£ 

•J>;HM  Sanooo 

i- 

? 

B 

t- 

i* 

•^ 

•* 

. 

•1I»M   10H 

k! 

2? 

S 

3 

6 

S 

0 

iraqjadns 

h 

s 

S 

S 

o 

S 

i 

: 

i 

•Mn)<uadaia^ 

It 

-t* 

*,-i 

0 

o* 

CO 

--; 

2 

( 

55 

wnss,^  a»mo 

f- 

o 

r- 

2 

, 

3 

CO 

•j»)a 
<"°J*q  ,.08  oj  p»jJ3j»j—  iunno«A. 

d 

CO 

t-^ 

c^ 

t- 

to 

:M 

"*! 

C-4 

'IHlno  JOJV.idaaS  JO  KDUSIOiy^ 

Wt 

-f 

S 

t- 

i 

S3 

" 

. 

•J  -H  P»)«>!POI 

P« 

= 

1 

O 

1 

a 

3; 

^ 

as 

r* 

S 

0 

s 

•MMD7 

CH 

z 

2 

S 

s 

s 

cc 

i 

S 

s 

5 

'd  'H  I^3!J13J[3 

E.H.P. 

00 

£ 

2 

1 

S 

-*< 

*# 

o 
^« 

° 

10 

••jjwoiix 

i 
w 

s 

S 

2 

0 

r- 

1 

.8 

w 

1 

•iv*l  jo  -on 

•" 

'- 

-^ 

« 

M 

" 

* 

«! 

n 

bJO 


U 

C 


I    ^ 
o 

PH     c 


/^         Q 
O3        ^ 

b^ 

<L>      O 

C    i — > 


. 

^3 

C     ^ 

_OJ         QJ 

'o    ?i 

f6  £ 

W   ^ 


Cu 


stations  are  designed  for  a  50  per 
cent  overload.  It  is  more  econo- 
mical to  install  a  pump  large 
enough  to  carry  this  overload  than 
to  have  one  whose  output  is  just 
sufficient  to  take  care  of  normal 
load.  The  circulating  pump  is 
rated  in  gallons  capacity.  In  order 
to  convert  this  rating  to  horse- 
power, it  is  necessary  to  multiply 
the  gallons  discharged  per  minute 
by  8.33  and  by  the  head  in  feet, 
dividing  the  product  by  33,000. 
(The  American  gallon  weighs  8.33 
pounds,  but  the  English  Imperial 
gallon  weighs  10  pounds.) 

The  connections  between 
pump  and  condenser  should  be 
made  as  short  and  straight  as 
possible,  and  also  the  suction  line 
should  be  direct.  Where  no  va- 
cuum pump  is  installed,  provision 
has  to  be  made  to  prime  the  cir- 
culating pump,  either  by  hand  or 
by  a  small  steam  ejector  or  other 
device.  When,  however,  a  vacuum 
pump  is  used  it  may  be  started, 
creating  a  vacuum  in  the  con- 
denser and  thence  in  the  circula- 
ting pump.  If  a  surface  condenser 
is  used  the  circulating  pump  may 
be  connected  by  a  small  pipe  to 
the  suction  of  the  air  pump. 

Reciprocating  pumps  employed 
as  circulating  water  pumps  may 
be  of  the  single  double-acting 
or  duplex  double-acting  type, 
depending  on  the  size  and  manu- 
facture. One  manufacturer  may 
favor  the  single  pump,  another  the 
duplex  type.  These  pumps  may 
also  be  either  steam  or  electrically 
driven.  In  a  few  turbine  stations 
the  dry  vacuum  pump  and  the 


266  STEAM-ELECTRIC  POWER   PLANTS. 

centrifugal  circulating  pump  are  operated  from  a  common  shaft.  A  more  common 
plan  is  to  have  one  steam  cylinder  operate  both  reciprocating  circulating  pump 
and  vacuum  pump;  with  this  design  the  pumps  and  condenser  may  be  erected 
on  one  bedplate,  with  the  condenser  placed  over  the  pumps.  This  arrangement 
has  advantages  and  disadvantages;  viz.,  as  both  pumps  have  to  operate  at  the 
same  piston  speed,  any  increase  in  load  on  one  involves  an  increase  in  speed  of 
the  other,  which  may  not  be  convenient.  It  is  the  best  practice  to  have  the  pumps 
individually  driven. 

Air  Pumps. — Air  pumps  are  practically  all  reciprocating,  although  there  are  a  few 
rotaries  on  the  market.  The  former  are  either  of  the  single  or  duplex  type,  steam  or 
motor  driven.  These  pumps,  as  well  as  all  other  auxiliaries,  should  be  of  as  simple 
and  durable  a  design  as  possible. 

A  very  efficient  type  of  air  pump  is  shown  in  Fig.  4.  This  type  is  known  as  the 
"  Edwards,"  and  is  single  acting,  handling  both  air  and  water.  This  pump  is  possibly 
the  most  simple  in  design  of  any,  requiring  no  suction  valves  and  no  packing  on  the 
plunger.  It  will  be  noticed  that  there  are  two  pumps  in  this  particular  case  which  are 
steam  driven,  while  in  the  accompanying  illustration,  Fig.  i,  the  pumps  are  motor 
driven,  being  connected  on  the  same  shaft  as  the  circulating  pump. 

Air  pumps  should  be  so  installed  that  all  parts  are  readily  accessible,  especially  if 
the  pump  is  horizontal,  for  they  all  require  considerable  attention,  if  high  vacuum  is 
carried,  in  order  to  keep  them  in  good  working  condition.  Sufficient  space  should 
be  allowed  for  removing  pistons,  care  being  taken  that  the  ends  of  the  pump  will  not 
abut  against  the  wall. 

Hot  Well  Pumps.  —  Hot  well  pumps  are  installed  with  surface  condensers  and 
take  care  of  the  water  of  condensation,  either  pumping  same  into  receiving  tank  or 
into  the  feed-water  heater.  They  are  either  centrifugal  or  reciprocating.  Usually 
condensers  are  provided  with  a  hot  well,  and  the  hot  well  pump  is  automatically  gov- 
erned by  the  height  of  the  water  in  this  well.  The  pump  must  always  be  located  at 
least  three  to  four  feet  below  the  water  line,  so  as  to  have  a  hydrostatic  head  on  the 
suction  valves  of  the  pump. 

House  Pumps.  —  The  duty  of  the  house  pump  is  to  supply  water  for  various  pur- 
poses, and  its  installation  is  of  special  importance  where  no  city  water  is  at  hand. 
Where  the  water  of  condensation  is  returned  to  the  boiler,  but  a  certain  percentage  is 
lost  by  leakage,  this  loss  must  be  made  up  by  the  house  pump.  The  usual  practice 
is  to  install  two  pumps,  so  that  one  may  be  held  in  reserve  in  case  of  emergency.  If 
the  water  is  used  for  boiler  feed,  wetting  ashes  and  toilet  purposes,  the  suction  may  be 
taken  from  the  intake  or  discharge  tunnel  and  pumped  into  tanks  located  at  a  height 
to  'give  sufficient  pressure.  Where  the  water  is  also  to  be  used  for  drinking  purposes, 
a  well  may  be  driven  or  the  suction  connected  to  the  city  main. 


PUMPING  MACHINERY. 


267 


1 

1          1 

1 

1 

1 

1          1 

1 

1 

1          1 

1 

1 

1 

1          1 

1 

1 

1 

1        1 

1 

1 

1 

1          1 

FIG.  3.     Centrifugal  Pump  Direct  Connected  to  Vertical  Engine  of  the  Wheeler  Condenser 

and  Engineering  Co. 


FIG.  4.  Edward's  Twin  Air  Pump,  Steam  Driven. 


268 


STEAM-ELECTRIC   POWER   PLANTS. 


Boiler  Feed  Pumps.  —  These  are  generally  of  the  outside  packed  plunger  recipro- 
cating type,  and  are  in  duplicate,  one  set  being  for  reserve.  It  is  good  practice  to 
install  a  number  of  small  pumps  rather  than  one  large  one.  They  should  be  centrally 
located,  in  order  to  facilitate  operation,  and  should  be  equipped  with  pressure  regulators, 
so  that  they  will  work  automatically.  The  feed  pumps  are  rated  in  gallons  per  minute 


FIG.  5.      Buffalo  Outside  End-Packed  Pump. 

capacity,  although  they  are  sometimes  rated  in  America  by  the  number  of  horse- 
power they  can  supply.  This  horse-power  means  boiler  horse-power  and  is  based  on 
40  pounds  of  water  per  hour  per  horse-power:  this  additional  amount  of  water  over 
the  usual  boiler  rating  of  30  pounds  is  to  allow  for  slippage  around  plunger. 

Oil  Pumps.  —  The  oil  pumps  may  be  classified  as  low  pressure  and  high  pressure. 
The  former  are  used  for  a  central  oiling  system,  either  pumping  the  oil  to  a  storage  and 
filtration  tank,  and  thence  by  gravity  to  the  engines,  or  from  the  filtration  tank  to  an 
elevated  storage  tank.  The  high-pressure  or  step-bearing  pumps  are  used  with  steam 
turbines,  supplying  pressure  under  the  shaft  so  that  the  turbine  shaft  revolves  upon  a 
film  of  oil.  These  pumps  are  frequently  operated  by  the  turbine  itself,  but  it  is  better 
practice,  especially  with  large  turbines,  to  have  a  separate  pump. 

Fire  Pumps.  —  The  fire  pumps  should  be  built  in  accordance  with  the  rules  of  the 
Board  of  Fire  Underwriters.  These  pumps  are  usually  built  for  100  pounds  pres- 
sure, but  it  may  be  necessary  to  increase  this  pressure  if  the  building  is  of  great  height. 
As  most  of  the  plants,  especially  large  ones,  are  entirely  fireproof,  there  are  no  fire 
pumps  installed.  This,  of  course,  increases  the  insurance  rate.  Where  fire  pumps 
are  installed,  they  must  be  placed  in  a  fireproof  compartment,  if  not  in  a  separate 
building,  and  they  also  must  have  steam  at  the  throttle  at  all  times. 

OILING   SYSTEM. 

Oil  Required.  —  It  is  of  vital  importance  to  install  an  oiling  system  in  all  power 
plants,  large  as  well  as  small.  A  complete  oiling  system  collects  the  oil  from  the  bear- 
ings, filters  it  and  returns  it  to  the  engine,  all  of  which  is  done  automatically.  From 
50  to  70  per  cent  of  oil  used  in  power  plants  is  wasted,  if  means  are  not  provided  to 
collect  same  as  mentioned  above. 


OILING  SYSTEM. 


269 


The  amount  of  oil  actually  consumed  with  a  reciprocating  engine  is  higher  than 
that  required  by  the  turbine.  It  also  depends  to  a  certain  extent  on  the  workmanship 
and  speed  of  engine  and  turbine.  The  Bavarian  Boiler  and  Engine  Inspection  Soci- 
ety made  a  thorough  investigation  of  the  subject  of  oil  consumption,  and  they  found 
that  in  compound  and  triple  expansion  engines  of  from  100  to  1,500  horse-power  the 
approximate  oil  consumption  per  horse-power  hour  amounted  to  two  grams,  while 
in  a  Parsons  steam  turbine  of  the  same  capacity  the  approximate  oil  consump- 
tion amounted  to  two-tenths  gram  per  horse-power.  However,  these  figures  mean 
the  oil  that  will  be  actually  consumed  by  evaporation,  etc. ;  a  greater  amount  of  oil  is, 
of  course,  required  for  flushing  these  bearings;  for  instance,  it  is  claimed  that  in  the 
Chelsea  plant  for  eight  5,ooo-K.W.  turbines,  33  gallons  of  oil  are  required  per  minute. 

Filtering  Tanks.  —  The  filtering  tank  should  be  so  located  that  the  oil  will  flow  to 
it  by  gravity.  The  tanks  should  be  installed  in  a  separate  building  or  a  fireproof 
compartment.  This  compartment  may 
also  contain  the  oil  pumps  as  well  as 
the  waste  cleaner  and  drier.  Provision 
to  guard  against  fire  is  necessary  in 
the  design  of  the  oil  room.  The  door 
should  be  so  arranged  that  it  will  shut 
automatically.  If  the  room  is  a  large 
one,  it  is  better  to  install  two  doors, 
one  large  and  one  small,  the  latter  one 
as  a  means  of  easy  escape  for  the 
attendant.  As  these  rooms  are  usually 
installed  in  the  basement,  it  is  of 
importance  to  protect  the  structural 
steel  with  brick  or  concrete.  The 
floor  should  be  provided  with  proper 
drainage,  as  it  is  necessary  frequently 
to  clean  the  tanks  and  filters. 

Many  of  the  larger  power  plants 
have  filtering  tanks  of  special  design, 
but  common  practice  is  to  install 
some  regularly  manufactured  article. 
The  tanks  should  be  in  duplicate,  or 
so  arranged  in  compartments  that  one 
compartment  may  be  cleaned  at  a 
time,  without  putting  the  entire  tank 
out  of  service.  Large  tanks  may  be  FIG.  i.  Burt  Oil  Filter, 

constructed  of    many    compartments; 

the  oil,  entering   through  cheese    cloth   or  light   canvas   filters,    passes  through  the 
compartments  at  a  low  velocity,  precipitating  any  foreign  substances.     The  filtering 


270 


STEAM-ELECTRIC   POWER   PLANTS. 


tanks  may  have  a  steam  coil  to  heat  the  oil,  thereby  increasing  the  speed  of  nitration 
and  causing  more  rapid  precipitation.  When,  however,  high-speed  engines  or  tur- 
bines are  used,  and  the  temperature  of  the  oil  returned  to  the  niters  is  high,  the  use 
of  the  steam  coil  may  be  dispensed  with. 

Very  frequently  the  oil  returned  from  the  engine  contains  a  certain  amount  of 
water;  it  is  necessary  to  abstract  this  water  with  the  filter.  Fig.  i  shows  a  typical 
oil  filter  of  this  type  as  manufactured  by  the  Burt  Manufacturing  Company.  The  oil 
entering  at  the  top  passes  through  the  waste  contained  in  the  center  chamber,  from 
where  it  passes  downward  through  the  pipe  "C,"  is  heated  by  the  steam  coil  and 
flows  upward  through  the  water  contained  in  the  lower  portion  of  the  tank.  This 
water  forces  the  oil  through  the  waste  "F"  into  the  pure  oil  compartment,  from  which 
it  is  drawn  off  and  re-used.  The  water  is  discharged  to  the  sewer  through  the  auto- 
matic water  separator,  shown  on  the  left-hand  side  of  the  cut. 

Another  very  efficient  oil  filter  is  shown  in  Fig.  2,  representing  the  Turner  system 
frequently  used  in  connection  with  the  Curtis  turbine.  As  will  be  seen  this  tank  is 

Section  1          Section.  2        Section    3         Section  4 


FIG.  2.     Turner  Oil  Filter. 


divided  up  into  four  sections,  the  oil  passes  through  the  filtering  material  of  each 
section,  having  its  temperature  raised  by  steam  coils  in  the  first  two  sections. 

A  very  efficient  oil  filtering  tank  is  shown  in  Fig.  3.  Similar  tanks  have  been 
installed  in  the  59th  and  74th  Street  power  houses,  New  York,  but  of  a  much  larger 
capacity  than  the  one  represented  in  this  cut.  These  filtering  tanks,  of  which  both 
plants  possess  two,  have  each  a  capacity  of  6,500  gallons  per  hour. 

The  tank  is  divided  into  chambers  by  partition  walls,  extending  alternately  to  the 
top  and  bottom  of  the  tank,  giving  the  oil  an  up  and  down  flow,  thus  increasing  pre- 
cipitation, which  will  be  greater  the  lower  the  velocity.  The  oil  before  entering  the 
tank  passes  through  canton  flannel  bags,  arranged  in  trays  as  shown  in  the  illustra- 


OILING   SYSTEM. 


271 


tion.  These  bags  are  removable  and  when  dirty  may  be  replaced  by  clean  ones.  The 
pipe  connections  are  such  that  any  chamber  may  be  separately  cleaned  without  shutting 
the  entire  filter  down. 


4  Suction  Bj  Pass. 


ooooooo 

ooooooo 

ooooooo  fl 

ooooooo 

ooooooo 

ooooooo  1 

ooooooo 
ooopooo 

o  oooo  oo 
ooc@ooo 

ooooooo  1 

0  0  O@0  O  O  I] 

r   OOOOOOO 

ooooooo 

OOOOOOO  1 

oaooooOi 

;   OO'OOOOO 

'O  O  O  O  O  <8cQ 

'o  o  o  o  o  6-6 

OOOOOOO  ll 

ooooxsoo  |1 

A  t 

A  . 

10!  

A 

->  -G"" 

if 

f-4 


1_ 


Cauton  Flannel 

3'Ueader. 


u 


FIG.  3.     Layout  of  an  Oil  Filter  Tank  System,  similar  to  which  some  are  installed 
at  the  59th  St.  and  74th  St.  Plants,  New  York.     (Power.) 

Oil  Pumps.  —  The  pumps  required  for  an  oiling  system  are  either  high  pressure 
or  low  pressure.  The  latter  are  used  with  a  central  oiling  system.  Duplicate  pumps 
should  be  installed,  in  order  to  keep  one  in  reserve. 

With  the  steam  turbine  high-pressure  pumps  are  required  to  purnp  the  oil  to  the 
step  bearing,  or  beneath  the  shaft  of  horizontal  turbines.  Some  types  of  turbines  have 
these  pumps  set  on  the  turbine  frame  and  operated  by  the  turbine  shaft,  while  with 
other  types  individual  pumps  are  used.  This  is  especially  necessary  where  a  number 
of  large  size  turbines  are  installed.  It  is  better  practice  to  install  several  small  size 
pumps  than  one  or  two  large  ones,  as  the  possibility  of  shut-down  is  thereby  lessened. 

With  the  vertical  Curtis  turbine  in  some  instances  water  is  used  for  the  step  bear- 
ing with  practically  the  same  results  as  those  obtained  with  the  use  of  oil.  The  entire 
equipment,  with  the  exception  of  the  filtering  tanks,  is  the  same  as  the  oiling  system. 

Supply  Tanks.  —  Frequently  it  is  necessary  to  install  one  or  two  elevated  supply 
tanks,  from  where  the  oil  is  fed  by  gravity  to  the  various  bearings.  These  tanks  must 
be  properly  vented,  and  where  more  than  one  tank  is  employed  they  must  be  inter- 


2/2 


STEAM-ELECTRIC   POWER   PLANTS. 


connected.     In  order  to  avoid  complicated  and  long  pipe  mains,  these  tanks  are  pref- 
erably placed  somewhere  in  the  center  of  the  plant. 

As  the  oil  is  used  over  and  over  again,  and  its  temperature  is  increased  each  time 
it  is  used  (especially  with  turbines  and  high-speed  engines),  it  is  usually  necessary  to 
cool  the  oil  by  means  of  water  cooling  coils  placed  in  the  supply  tank. 

Oil  Piping. — The  return  pipes  leading  the  oil  from  the  various  bearings  or  col- 
lecting pans  to  the  filtering  tank  may  be  of  either  wrought  or  cast  iron;  the  former  is 

preferable,  however,  for  small  pipes.  If  wrought 
iron  is  employed  screw  fittings  may  be  used.  In 
order  to  secure  a  good  gravity  flow  for  the  oil  the 
pipes  should  be  pitched  at  least  one  inch  in  every 
ten  feet.  Where  many  returns  are  connected  to  one 
common  header,  provision  has  to  be  made  for  the 
removal  of  air.  This  is  accomplished  by  placing 
^-inch  or  f-inch  vent  pipes  on  the  header.  These 
vents  must  extend  above  the  highest  point  in  the 
return  piping,  so  that  if  the  pipe  discharging  to  the 
filter  should  be  plugged  the  oil  will  not  escape 
through  the  vents.  To  facilitate  cleaning  the  pipe, 
it  is  good  practice  to  install 
crosses  instead  of  tees  in  the 

/e£i/£fmi.r£  header,  one  leg  being  plugged. 

The  supply  pipes  from  the 
filter  to  the  elevated  tank  and 
also  the  pipe  from  the  tank 
to  the  engines  should  be  made 
of  brass  or  copper.  This  is 
absolutely  necessary,  as  steel, 
wrought-iron  or  cast-iron  pipe 
contains  a  scale  which  oil 
loosens,  and  if  this  scale  gets 
into  the  bearings  it  is  liable 
to  cause  considerable  damage. 
Galvanized  iron  pipe  has  been 
tried  for  supply  piping,  but 
~\  |  experience  has  shown  that  the 

galvanizing  will  wear  off  and 
the  pipe  will  scale  as  badly  as 

a  black  iron  pipe. 
FIG.  4.     Piping  for  Oiling  System  of  Curtis  Turbine.  ^  supply  pipcg  ^  pknts 

employing  reciprocating  engines  are  low  pressure,  while  those  where  turbines  are  used 
are    high  pressure.     All  return  pipes  are  low  pressure.     The  pressure  employed  in 


^GAUGf.  GLASS 

fcOf?    CHARGING 
\A/F>    CHAMBER 

THR££  WAY COCH 


OILING  SYSTEM.  273 

high-pressure  systems  varies  with  the  size  of  turbines  installed;  for  instance,  with 
5,ooo-K.W.  Curtis  turbine  the  pressure  used  would  be  about  800  pounds  per  square 
inch;  it  varies  also  with  the  types  of  turbine  employed. 

It  is  essential  to  keep  the  pressure  of  oil  constant.  This  may  be  accomplished  by 
weight  accumulators,  or  a  tank  with  an  air  pressure  above  the  oil.  The  weight  accumu- 
lators are  unsightly  and  occupy  a  great  deal  of  space,  while  the  tank  is  small  and  gives 
just  as  good  results,  is  less  expensive,  and  may  be  placed  in  an  inconspicuous  corner. 

Automatic  throttle  valves  must  be  placed  in  the  steam  connection  to  the  pump,  and 
properly  piped  with  the  air  tank  or  weight  accumulators.  Some  types  of  turbines 
require  that  bafflers  be  installed  in  the  pipe  line  near  the  bearings.  These  bafflers  are 
so  arranged  that  they  take  up  any  shock  which  may  result  from  the  stroke  of  the  pump. 

The  distributing  pipes  on  the  turbine  are  usually  supplied  by  the  manufacturers. 
The  plant  designer's  duty  is  to  connect  these  to  the  oil  mains,  tanks  and  pumps. 


CHAPTER  VII. 
ELECTRICAL  EQUIPMENT. 

Introductory.  — The  development  of  the  electrical  features  of  power  plants,  espe- 
cially the  design  of  switchboards,  has  become  so  specialized  in  recent  years  that  the 
mechanical  engineer,  the  power  plant  designer,  has  less  and  less  to  do  with  this  depart- 
ment. Owing  to  this  fact  he  is  becoming  less  familiar  with  this  part  of  the  work  and, 
as  with  modern  power  plants  and  increased  transmission  distances  and  potentials,  the 
electrical  equipment  is  constantly  requiring  changes  and  improvements,  a  knowledge 
of  this  subject  is  becoming  more  difficult  of  attainment  and  simultaneously  of  more 
importance.  As  reliability  of  service  and  economy  of  operation  are  both  of  prime 
importance,  it  is  necessary  that  the  mechanical  and  electrical  engineers  work  in  per- 
fect harmony.  The  following  discussion  of  the  electrical  equipment  is  for  the  pur- 
pose of  supplying  the  information  required  by  the  mechanical  engineer  for  the  proper 
performance  of  his  work,  rather  than  for  the  complete  design  of  the  electrical  outfit; 
however,  it  must  be  remembered  that  a  large  part  of  the  mechanical  design  is  affected 
by  the  electrical  features  and  vice  versa. 

Similar  to  the  mechanical  equipment  of  the  plant,  the  electrical  apparatus  should 
be  divided  up  into  the  unit  system,  e.g.,  each  generator  and  exciter  should  have  its  own 
panel  on  the  switchboard.  This  simplifies  the  operation  of  the  entire  plant. 

Generators.  —  The  electrical  characteristics  of  the  generator,  voltage,  etc.,  must 
be  decided  upon  by  the  electrical  engineer  and  depend  upon  the  transmission  system. 
While,  of  course,  the  capacity  of  the  units  depends  largely  upon  the  load  diagram, 
which  is  usually  plotted  by  the  electrical  engineer,  it  also  depends  upon  the  various 
characteristics  and  economies  of  the  prime  movers,  and  must,  therefore,  be  considered 
by  the  mechanical  engineer. 

If  reciprocating  engines  are  used,  the  generators  are  mounted  directly  upon  the 
main  shaft  and  care  must  be  exercised  by  the  mechanical  engineer  to  have  sufficient 
space  around  the  generator  and  in  the  pit  to  give  easy  access  to  all  parts  for  repairs, 
etc.  Railings  must  be  installed  to  guard  against  accidents.  Anchor  bolts  for  the 
generator  frame  should  be  similar  to  those  used  for  the  engines,  in  order  to  secure 
uniformity. 

Where  turbines  are  employed  little  attention  to  the  generators  is  required  from  the 
mechanical  engineer,  as  they  are  carried  on  the  turbine  bedplate  itself,  while  in  case 
of  certain  turbines,  as  the  vertical  Curtis,  where  galleries  are  necessary,  care  should  be 

274 


ELECTRICAL  EQUIPMENT. 


2/5 


u 

T3 

E 


W) 
O 


rt 

O 


C/2 

bJD 

3 
O 


276 


STEAM-ELECTRIC   POWER   PLANTS. 


exercised  to  have  these  galleries  similarly  located  and  designed  with  the  other  galleries 
required  in  the  power  plant.  This  is  of  especial  importance  where  access  from  one 
gallery  to  another  is  necessary.  A  notable  instance  of  these  conditions  is  that  of  the 
plant  of  the  Delaware  &  Hudson  Company  at  Mechanicville,  N.Y.  (at  present  under 
construction),  where  galleries  of  the  Curtis  turbines  are  directly  connected  with  the 


FIG.  2.     High-Tension  Feeder  Cables,  in  Basement,  entering  Conduits, 
Long  Island  City  Plant. 

switchboard  galleries,  thus  enabling  the  switchboard  attendants  to  take  care  of  the  gene- 
rators, which  require  little  attention,  making  a  material  reduction  in  the  operating  force. 
With  certain  types  of  turbo-generators,  for  instance,  the  Westinghouse-Parsons, 
air  ducts  have  to  be  provided  for  cooling  purposes,  owing  to  the  fact  that  the  generators 
are  of  the  closed  type,  thus  preventing  natural  ventilation.  These  air  ducts,  which  arc 
built  of  very  light  material,  may  be  Carried  through  or  near  a  basement  window,  so  as 
to  give  a  supply  of  fresh  air.  They  must  be  provided  with  a  fine  wire  screen,  so  as  to 
keep  out  foreign  material. 


aopf— 

-dot  J— , 

.-  dokoL 


278  STEAM-ELECTRIC   POWER  PLANTS. 

Exciters. — The  exciters  may  be  either  steam  or  motor  driven,  or  a  combination  of 
both.  With  the  Parsons  turbine  the  exciter  is  sometimes  mounted  directly  upon  the 
turbine  shaft,  as  will  be  noticed  in  the  article  on  turbines.  Without  question,  the 
motor-driven  exciter  is  more  economical,  as,  for  instance,  a  non-condensing  high- 
speed engine  or  turbine  may  easily  consume  from  40  to  50  pounds  steam  per  I.H.P. 
hour,  while  when  current  is  drawn  from  the  main  bus-bar  system,  which  in  turn 
receives  its  power  from  the  main  generator  unit,  the  steam  consumption  is  from  12 
to  14  pounds  per  I.H.P.  hour.  It  must  be  remembered  that  the  efficiency  of  a 
motor  generator  is  approximately  80  per  cent,  which  would  give  an  equivalent  steam 
consumption  of  from  13  to  15  pounds  per  I.H.P.  hour.  With  motor-driven  exciters 
it  is  important  to  install  a  storage  battery.  Since  in  practically  all  high-tension  plants, 
a  storage  battery  is  required  to  operate  oil  switches,  etc.,  it  might  as  well  be  increased 
so  as  to  have  sufficient  capacity  to  float  on  the  exciting  bus-bars,  thus  giving  a  more 
uniform  excitation  and  at  the  same  time  taking  care  of  peak  loads. 

Another  practice  is  to  install  a  combined  motor  and  steam-driven  exciter  outfit, 
in  which  case  the  steam-driven  exciter  will  start  up  the  plant  while  the  motor-driven 
exciters  are  used  under  ordinary  circumstances.  With  this  system,  of  course,  a  storage 
battery  is  not  so  essential. 

Careful  attention  must  be  given  to  the  choosing  of  the  proper  size  of  exciters,  since 
while  these  are  small  items  in  the  first  cost  of  the  total  plant,  they  are  of  prime  impor- 
tance for  the  reliability  of  operation.  Frequently  the  error  is  made  of  installing  only  a 
single  exciter  unit  of  capacity  sufficient  to  handle  the  whole  plant.  This  is  decidedly 
poor  engineering,  as  at  least  one  (depending  upon  size  of  plant)  exciter  should  always 
be  kept  in  reserve.  Where,  however,  the  conditions  are  such  as  to  make  it  undesirable 
to  install  double  the  exciter  capacity  required,  the  unit  should  be  divided,  so  that  in 
case  of  emergency  the  entire  plant  would  not  lie  idle. 

The  size  of  the  exciters  depends  upon  the  character  of  the  plant,  varying  from 
\  to  2  per  cent  of  the  total  generator  output  (including  reserve  unit).  For  instance, 
a  20,000  K.W.  plant,  normal  capacity,  should  have  two  100  K.W.  exciters. 

Generator  Leads.  —  All  leads  between  generators,  exciters  and  the  bus-bars  should 
be  carried  in  the  basement,  where  there  is  one,  or  in  clay  ducts  or  iron  pipe  imbedded 
in  the  concrete  of  the  floor.  In  the  latter  case,  manholes  must  be  provided  at  suitable 
places  to  give  ready  access  for  pulling  in  the  cable.  It  is  desirable  to  avoid  unneces- 
sary bends  and  run  as  straight  to  the  switchboard  as  possible.  Where  galleries  are 
used,  as  with  the  Curtis  turbines,  the  generator  leads  may  run  under  the  gallery  in  iron 
pipes. 

Switching  Room.  —  Before  the  dimensions  of  the  plant  are  determined,  the  space 
required  for  the  switching  rooms  should  be  thoroughly  studied  in  connection  with  a 
competent  electrical  engineer,  for  too  frequently  mistakes  are  made  in  designing  this 
part  of  the  plant  too  small,  resulting  in  unnecessary  crowding  of  apparatus.  One,  two 
or  three  floors  may  be  provided,  depending  upon  the  system  adopted,  and  it  is  the 


ELECTRICAL  EQUIPMENT. 


279 


duty  of  the  electrical  engineer  to  decide  how 
much  room  he  requires  for  the  high-tension 
bus-bars,  oil  switches  and  the  various  switch- 
boards, etc.  The  switching  room  may  be 
located  either  at  one  end  of  the  plant  or 
running  at  the  side  and  occupying  the  entire 
length  of  the  generating  room,  and  it  should 
be  separated  from  the  latter  by  a  partition 
wall,  either  of  fireproof  material  or  glass,  in 
order  to  keep  all  dirt  away  from  high-tension 
apparatus.  The  latter  is  preferable  where, 
owing  to  the  general  arrangement,  no  light 
can  be  thrown  into  the  switching  room.  It 
must  here  be  remembered  that  all  outside 
windows  in  the  switching  room  must  be  kept 
securely  closed,  so  as  to  prevent  any  foreign 
material,  rain,  etc.,  from  blowing  in  and 
causing  serious  grounds  or  short  circuits.  It 
is  also  important  to  keep  all  roof  leaders, 
etc.,  away  from  the  switching  apparatus, 
as  leakage  or  dripping  due  to  condensation 
may  cause  serious  damage.  In  some  not- 
able instances  entirely  separate  buildings 
are  used  for  switching  purposes.  (Port  Mor- 
ris station,  New  York,  and  Fisk  Street  plant, 
Chicago.) 

The  accompanying  illustration,  Fig.  4, 
represents  the  switching  compartments  of  the 
new  "Waterside"  station  of  the  New  York 
Edison  Company, 


I 


while  Fig.  5  shows 
a  section  through 
the  switching  com- 
partment of  the 
59th  Street  plant, 
New  York.  Both 
stations  are  of  re- 
cent design  and 
may  serve  as  good 
examples  of  modern 
American  practice. 
An  example  of 
British  practice  is 
shown  in  Figs. 


FIG.  4.  Switch  Room 
(10,000  Volt),  Waterside 
No.  2,  New  York. 


280 


STEAM-ELECTRIC   POWER   PLANTS. 


6  and  6a,  which  was  presented  before  the  Institution  of  Electrical  Engineers, 
London,  by  Messrs.  Merz  and  McLellan,  in  a  paper  on  the  design  of  power 
plants. 


FIG.  5.     Cross-Section  through  Switch  Room,  $gth  St. 
Plant,  New  York. 

The  main  controlling  board  should  be  installed  in  the  gallery  above  the  bus-bars 
and  oil  switches,  so  that  the  operator  may  easily  overlook  the  entire  generating  room. 
This  might  be  done  by  having  large  openings  in  the  partition  wall,  between  the  gen- 


ELECTRICAL  EQUIPMENT. 


28l 


GENERATOR  PANEL.    FEEDER  PANEL. 

FRONT  VIEW. 
FEET  j      Q 


FEEDER  PANEL    GENERATOR  PANEL 
BACK  VI&W 


SCALE 

2$4S$?       $9 K)  FtET. 


BACK  AND  FRONT  VIEW  OF  H.T.  SWITCH   GEAR. 
CARVILL&      POWER     STATION 


FIG.  6. 


282 


STEAM-ELECTRIC   POWER   PLANTS. 


B.-BUS    BAR 

B.I.S.-  BUS  BAR   ISOLATING    SWITCH. 
C.O.S.-  BUS  BAR   CHANGE    OVER   SWITCH 

D.- DIVIDING     BOX. 

M.-MAIN    OIL   BREAK    SWITCH. 

E.-  CABLE    END. 
P.-  POTENTIAL  TRANSFORMER*. 
S.-  SPARK     GAPS. 
P.I.5.-  FEEDER    ISOLATING    SWITCH. 


MAIN  SWITCH 
QALLERY. 


crating  and  switching  rooms,  or  by  installing  a  balcony 
overlooking  the  generating  room.  It  is  good  practice 
to  enclose  this  part  of  the  switching  room  in  glass. 

Staircases  must  be  provided  between  the  floors  to 
give  easy  access  to  the  various  compartments  and 
pieces  of  apparatus.  These  should  always  be  in 
straight  runs  where  possible.  The  use  of  spiral 
stairs  is  generally  proof  that  the  switching  room  was 
laid  out  too  small.  All  staircases,  of  course,  should  be 
made  of  iron. 

Wiring  Diagram. — The  wiring  system  in  the  elec- 
trical part  of  the  plant 
corresponds  exactly  with 
the  piping  in  the  steam 
part.  It  should  be  made 
as  simple  and  at  the 
same  time  as  flexible  as 
possible.  The  wiring 
diagram  should  be  so 
laid  out  as  to  avoid  as 
much  as  possible  any 
interruption  to  the 
service,  and  the  appa- 
ratus should  be  arranged 
so  that  in  case  of  acci- 
dent the  disabled  section 
may  be  easily  cut  out. 
For  this  purpose  section- 
alizing  switches  must  be 
installed,  and  in  order  to 
make  repairs  on  these 
switches,  disconnecting 
switches  must  be  placed 
on  each  side. 

The  bus-bars  are 
arranged  in  the  "single," 
"double"  or  "ring  sys- 
tem." Where  a  plant 

1 '          '  serves  for  both  light  and 

FIG.  6a.  .         °  . 

power     it     is    advisable 

to  install  two  bus-bar  systems,  keeping  the  two  services  separate,  and  double-throw 
switches  so  arranged  as  to  use  any  generator  for  light  or  power.      These    bus-bars 


INSTRUMENT 

TRANSFORMER 

GALLERX 


GENERATOR  PANEL. 


FEEDER  PANEL. 


CROSS    SECTION    or  HIGH    TENSION    SWITCH    GEAR. 
CARVIU.E   POWER   STATION. 


FEET.|    o    i    i 


SCALE. 

3     4      5     6 


7    8    a 


ELECTRICAL  EQUIPMENT. 


283 


o 

r* 

o; 


PH 


•4-J 

ON 


V 

c 
<u 

O 


t^ 

o 


284 


STEAM-ELECTRIC    POWER    PLANTS. 


are  frequently  distinguished  as  main  and  auxiliary  bus-bars.       The  same  may  also 
be  applied  to  the  outgoing  feeder  systems. 

It  is  not  the  intention  to  give  a  description  of  the  wiring  diagram  of  the  complete 
equipment,  but  Fig.  7  shows  the  wiring  diagram  of  the  complete  plant  of  the  59th  Street 


BATTERY* 


THESE   LEADS    FOR    EXCITING  GEN 
FIELD    DIRECT  FROM    BUS-  BARS. 


EXCITING      CIRCUIT     DIAGRAM. 
CARVILLE.     POWER     STATION. 

FIG.  8. 


power  house,  New  York.  By  studying  this  cut  it  will  be  seen  that  the  connections  of 
the  machinery  for  the  entire  power  plant  are  included,  wrhile  in  Fig.  8  only  the  exciter 
wiring  of  the  Carville  power  station  is  shown.  Other  wiring  diagrams  are  given  in 
Chapters  X  and  XI  on  various  power  plants. 


ELECTRICAL  EQUIPMENT. 


285 


Bus-Bar  Chambers.  —  Bus-bar  chambers  should  be  made  fireproof,  either  of  rein- 
forced concrete  or  brick.  All  compartments  should  be  so  laid  out  as  to  give  easy 
access  to  any  piece  of  apparatus. 

The  floors  for  carrying  the  bus-bars  and  oil  switch  chambers  must  be  calculated 
according  to  the  weights  to  be  carried,  depending,  of  course,  upon  the  arrangement  and 
the  voltage  and  power  employed.  Four  hundred  pounds  per  square  foot  is  usually 
chosen  for  a  system  of  11,000  volts. 

Oil  Switches.  —  Oil  switches  are  used  where  high  tension  is  employed  and  are  either 
motor,  solonoid  or  hand  operated.  The  first  is  most  favorable  for  high  voltage.  The 


FIG.  9.     Oil  Switches  and  Bus-Bar  Compartments,  5Qth  St.  Plant,  New  York. 


oil  chambers  containing  the  switches  are  set  in  compartments  made  of  concrete  or 
brick,  similar  to  those  used  for  the  bus-bars.  On  top  of  these  cells  are  mounted  the 
motors,  which  are  operated  from  a  centrally  located  controlling  board.  These  switch 
cells  should  be  so  located  as  to  give  easy  access  to  all  parts  of  the  switch  and  switch 
mechanism,  and  the  oil  chambers  so  arranged  as  to  be  easily  removable  without  dis- 
turbing the  mechanism  of  the  switch.  The  switch  cells  should  be  provided  with  a 
removable  door  made  of  wired  glass,  slate,  or  asbestos  lumber  held  in  a  wooden  frame, 
so  that  the  oil  chamber  may  be  easily  removed.  Fig.  9  shows  the  coil  switches  and 
bus-bar  compartments  of  the  59th  Street  power  plant,  New  York.  As  this  photograph 


286 


STEAM-ELECTRIC   POWER   PLANTS. 


S    5   -a 


ELECTRICAL  EQUIPMENT. 


287 


e 

<u 

O 


*  TJ 

>-<  C 

O  rt 

tM  73 

s  I 


o 

.      U 

X      « 


0  1 

&  6 

>  1 

§  § 

o,  u 


288 


STEAM-ELECTRIC   POWER   PLANTS. 


was  taken  during  course  of  erection,  the  system  of  arrangement  and  method  of  con- 
struction are  more  clearly  shown. 

Continental  practice  is  to  operate  these  oil  switches  even  with  very  high  voltages 
by  hand  and  a  system  of  levers,  as  will  be  seen  in  Fig.  10,  showing  a  6,ooo-volt  bus-bar 
room  of  the  Obermatt  station  of  Lucerne.  As  will  be  noticed,  they  are  operated  from 
the  floor  above.  Attention  is  also  called  to  the  fact  that  the  bus-bars  are  not  placed  in 
separate  compartments,  as  is  customary  in  America  and  Great  Britan.  This  practice, 
of  course,  can  be  adopted  only  where  plenty  of  space  is  available.  It  will  be  noticed, 
however,  that  the  two  bus  systems  are  separated  by  a  shelf. 

This  station,  which  was  designed  and  installed  by  the  Ocrlikon  Company,  Zurich, 
Switzerland,  is  one  of  the  latest  and  most  modern  illustrations  of  recent  European 
practice,  especially  in  regard  to  the  electrical  equipment,  and,  therefore,  additional 


FIG.  1 4.    Architectural  Features  of  a  Low-Tension  Switchboard  at  "  Bille  "  Plant,  Hamburg. 

(Siemens  Schuckert  Co.). 

cuts  will  prove  of  interest.  The  system  is  designed  for  multiple  voltage  service.  Each 
piece  of  apparatus  is  mounted  in  a  separate-  compartment,  no  covers,  however,  being 
provided. 

Switchboard.  —  The  main  switchboard  and  controlling  boards  should  be  centrally 
located  in  order  to  facilitate  operation.     From  here  all  high-tension  switches  are  con- 


ELECTRICAL  EQUIPMENT. 


289 


trolled  by  low-tension  current  devices.  The  switchboard  itself  is  usually  made  of 
enameled  slate  or  marble  on  a  structural  steel  or  pipe  frame,  without  any  further 
ornamental  decoration.  A  different  practice  is  in  vogue  on  the  Continent  of  Europe, 
where  the  boards  are  made  of  white  marble  mounted  on  frames  of  very  elaborate 
design.  Two  examples  of  this  practice  are  illustrated  in  Figs.  14  and  15,  the  former 
representing  a  switchboard  at  a  power  plant  in  Hamburg,  Germany,  designed  by  the 
Schuckert  Company  of  Nuremberg.  It  will  be  noticed  that  this  is  a  low-tension 
switchboard,  the  slabs  of  white  marble  being  framed  with  an  elaborate  ornamental 
wooden  molding.  Of  course  it  must  be  remembered  that  this  board  was  built  before 
high-tension  alternating  current  came  into  universal  use,  and  forced  the  adoption  of 
iron  frames,  as  seen  in  Fig.  15,  representing  the  ornamental  features  of  modern 
design.  A  notable  departure  from  this  practice  is  that  common  in  Switzerland 


FIG.  15.     Type  of  Modern  German  Switchboard  at  Siegen. 
(Siemens  Schuckert  Co.) 

and  recently  also  used  in  other  countries,  namely,  of  mounting  the  instruments  and 
controlling  levers  on  a  so-called  instrument  post.  One  of  these  posts  is  usually  pro- 
vided for  each  generator  and  exciter,  an  example  of  which  is  given  in  one  of  the  accom- 
panying illustrations  (Fig.  n).  The  great  advantage  of  this  feature  is  that,  during 
operation,  the  attendant  faces  the  generator  room,  instead  of  turning  his  back,  as  is 


290 


STEAM-ELECTRIC   POWER   PLANTS. 


necessary  in  the  ordinary  practice.  For  controlling  the  outgoing  feeders,  switchboards 
are  installed.  If  current  is  used  for  both  light  and  power,  the  bus-bars  as  well  as  the 
controlling  panels  should  be  kept  separate.  The  entire  switchboard  should  be  self- 
explanatory,  and  in  order  to  facilitate  operation,  especially  for  new  hands,  a  diagram 
of  the  wiring  system  should  be  mounted  in  a  convenient  place.  Care  must  be  taken 
to  have  all  parts  of  the  system  thoroughly  protected  by  automatic  devices. 

Storage  Battery.  — The  capacity  of  the  storage  battery  depends  entirely  upon  its 
purpose,  as  has  been  previously  stated.  It  may  be  installed  only  for  operating  the 
high-tension  switches  and  assisting  the  auxiliary  machinery,  or  for  lighting  the  station 
in  case  of  emergency. 

Storage  batteries  are  desirable  for  maintaining  a  constant  voltage  on  the  exciter 
bus-bars,  which  is  of  especial  importance  where  motor-driven  exciters  are  run  direct 
from  the  main  bus-bars.  The  fluctuation  of  the  generator  voltage  will  affect  the 
excitation  current,  thus  aggravating  the  former.  Besides  this  a  storage  battery  float- 
ing on  the  exciter  buses  may  easily  take  care  of  peak  loads.  In  case  of  break-down  of 
the  exciter  units,  either  motor  or  steam  driven,  the  storage  battery  will  give  excellent 
service. 

It  must,  however,  be  remembered  that  the  first  cost  and  maintenance  of  a  storage 
battery  is  high,  and  the  depreciation  is  approximately  10  per  cent  per  annum. 


FIG.  1 6.     Load  Diagram  on  Plant  of  the  San  Francisco,  Oakland  and  San  Jose  Ry.  Co. 

Fig.  16  shows  the  load  diagram  of  the  power  plant  of  the  San  Francisco,  Oak- 
land &  San  Jose  Railway  Company,  clearly  illustrating  the  effect  of  a  storage  battery 
on  railway  power  service.  It  will  be  noticed  that  the  minimum  current  is  about  200 
amperes,  while  the  maximum  is  about  2,200.  The  division  of  the  load  between  the 
battery  and  the  generators  is  also  shown  in  the  chart,  the  fluctuation  of  some  2,000 
amperes  being  taken  care  of  by  the  battery.  Although  there  are  not  now  many 


ELECTRICAL  EQUIPMENT.  291 

engineers  who  advocate  direct  current  for  long-distance  transmission  for  railroading 
or  lighting  the  storage  battery  still  holds  a  very  prominent  place  in  sub-stations,  and 
there  are  many  instances  where  storage  batteries  are  used  in  the  main  power  plants. 
In  railway  practice  the  battery  is  alwrays  installed  with  a  constant-current  booster,  so 
adjusted  that  the  load  on  the  generator  is  uniform  and  the  peaks  are  taken  on  the 
battery. 

In  order  thoroughly  to  ventilate  the  battery  room,  fans  are  usually  installed.  These 
fans  are  best  operated  by  motors,  as  it  is  difficult  to  bring  steam  pipes  across  the  gen- 
erator room  to  the  switching  room. 


CHAPTER   VIII. 
THE    DESIGN   OF  SMALL   POWER  PLANTS.* 

Introductory.  —  Notwithstanding  the  fact  that  the  majority  of  central  stations  are 
below  3,000  K.W.  capacity,  those  usually  discussed  are  of  larger  capacity.  This  may 
be  due  not  only  to  the  prominence  of  the  plant  and  the  exceptionally  large  size  of 
prime  movers,  but  also  to  the  fact  that  they  supply,  either  directly  or  indirectly,  the 
needs  of  a  large  number  of  people.  The  record-breaking  advertising  of  the  various 
manufacturers  is  also  a  potent  factor  in  increasing  the  interest  in  these  larger  plants, 
since  of  course  the  larger  the  plant  the  more  notoriety  gained  by  the  company  supplying 
the  machinery,  as  well  as  by  the  designer  of  such  a  plant.  Such  power  plants  are,  how- 
ever, as  above  stated,  only  a  very  small  percentage  of  the  total  number  of  plants.  The 
design  of  these  plants  in  many  respects  is  an  entirely  different  proposition  from  that 
of  the  large  central  station,  since  what  may  be  a  small  item  in  the  latter  may  prove  to 
be  a  large  percentage  of  the  total  first  cost  of  the  small  plant.  Not  only  from  a  finan- 
cial point  of  view  is  it  a  different  proposition,  but  also  in  the  technical  design.  Inas- 
much as  the  break-down  of  a  single  unit  in  a  small  plant  constitutes  the  disability  of  so 
much  larger  percentage  of  the  complete  equipment,  so  much  more  important  is  the 
necessity  for  break-down  units  in  the  former.  As,  however,  a  small  station  cannot  be 
equipped  with  as  large  a  number  of  emergency  units  as  are  frequently  found  in  larger 
plants,  it  becomes  of  vital  importance  to  select  the  proper  size  of  the  main  machinery, 
such  as  boilers,  prime  movers,  etc.  It  is,  therefore,  the  author's  intention  to  discuss 
briefly  the  various  questions  encountered  in  the  design  of  a  small  power  plant. 

There  are  many  items  affecting  the  decision  in  regard  to  the  requisite  capacity  of 
the  plant  as  well  as  the  individual  prime  movers,  such  as  urban  and  interurban  rail- 
way service,  municipal  and  private  lighting,  character  and  amount  of  power  load  for 
industrial  and  domestic  purposes,  possible  forms  of  contract,  etc.  There  is  not  space 
here  to  discuss  more  fully  this  preliminary  although  very  important  special  subject, 
as  the  above  factors  vary  so  widely  with  the  character  of  the  town;  and,  therefore, 
assuming  that  these  points  have  been  settled,  we  will  confine  ourselves  to  the  detail  of 
designing. 

Assuming  the  plant  to  be  for  supplying  light  and  power  to  a  given  community 
scattered  over  a  considerable  area,  the  current  generated  in  the  power  plant  will  be 
2,300  volts,  sixty-cycle,  three-phase  alternating,  being  stepped  down  at  sub-stations. 
On  account  of  the  character  of  the  load  curve  we  will  assume  that  it  has  been  decided 

*  See  author's  original  article,  Electrical  Review,  April  ao,  27,  May  4,  1907. 
2Q2 


SMALL  POWER  PLANTS. 


293 


to  install  a  plant  of  2,250  rated  horse-power  or  1,500  K.W.  This  plant  shall  consist  of 
three  75O-K.W.  units,  one  of  which  will  be  always  in  reserve,  while  the  building  itself 
will  be  large  enough  to  accommodate  a  fourth  unit  of  equal  or  greater  capacity  in 
order  to  meet  the  increasing  demand  after  the  first  few  years.  The  plant  will  be  run 
condensing. 

As  these  prime  movers  are  so  designed  as  to  operate  under  an  over-load  of  50  per 
cent,  the   maximum  combined    capacity  of   the  two  prime  movers  will    therefore   be 


FIG  i.     Superstructure  (Electrical  Review). 

2,250  K.W.  In  order  to  choose  the  proper  size  of  boilers  it  is  necessary  to  know 
the  steam  consumption  of  the  prime  movers  and  the  auxiliaries,  assuming  that 
the  latter  are  steam  driven.  Practice  has  proven  that  the  auxiliaries  consume  (includ- 
ing leakage,  drip,  etc.)  from  five  to  ten  per  cent  of  the  total  steam  consumption, 
although  there  are  plants  where  this  runs  up  as  high  as  15  per  cent,  and  some  notable 
instances  in  recent  prominent  turbine  plants  where  this  is  lower  than  5  per  cent. 


294  STEAM-ELECTRIC   POWER    PLANTS. 

Assuming  further  that  the  plant  is  located  in  a  remote  district  where  skilled  labor 
is  scarce,  the  water  consumption  will  be  materially  increased  on  account  of  the  waste 
incident  to  too  frequent  blowing  off  of  boilers,  draining  of  main  steam  pipes  of  the 
main  prime  movers  and  auxiliaries,  etc.  Under  such  conditions  the  liberal  consump- 
tion of  20  pounds  per  K.W.  hour  (including  auxiliaries,  etc.)  is  assumed.  This  results 
in  a  total  water  consumption  of  1,500  X  20  =  30,000  pounds  per  hour.  Assuming 
that  water-tube  boilers  have  been  selected  and  that  3  pounds  of  water  will  be  evapo- 
rated per  square  foot  of  heating  surface,  boilers  with  10,000  square  feet  of  heating 
surface  would  be  required.  This,  however,  assumes  normal  conditions  for  the  boilers, 
(with  an  overload  of  50  per  cent  on  the  turbines);  an  overload  of  approximately  35 
per  cent  being  good  practice  for  maximum  economical  forcing  of  boilers.  Making 
allowance  for  this  overload,  approximately  11,000  square  feet  of  heating  surface  is 
required.  As  it  is  American  practice  to  rate  boilers  in  horse-power  and  10  square  feet 
of  heating  surface  in  a  water-tube  boiler  is  equivalent  to  one  "boiler  horse-power," 
1,100  horse-power  would  be  required,  this  giving  a  ratio  of  0.73  boiler  horse-power 
per  K.W. 

Type  and  Size  of  Plant.  —  At  least  two  boilers  should  be  installed  for  each  prime 
mover,  which  would  necessitate  four  275-horse-power  boilers  (2,750  square  feet).  As, 
however,  the  boilers  require  frequent  cleaning  and  repairing  and  as  there  is  one  spare 
prime  mover,  the  same  spare  capacity  of  boilers  should  be  installed.  Of  course,  space 
must  also  be  left  for  two  more  boilers  to  supply  the  future  prime  mover  when  installed. 
As  will  be  seen  in  the  accompanying  plan,  Fig.  2,  the  boiler  house  runs  parallel  to  the 
generating  house,  the  boilers  being  arranged  in  one  row,  in  batteries  of  two.  The 
chimney  is  located  between  the  fourth  and  fifth  boilers,  thus  giving  a  symmetrical 
layout.  Allowing  5  feet  clearance  between  two  adjacent  batteries  and  5  feet  between 
the  batteries  and  the  end  walls,  with  23  feet  between  boilers  Nos.  4  and  5,  which  space 
is  occupied  by  the  chimney,  boiler-feed  pumps,  feed-water  heater,  etc.,  and  assuming 
that  a  battery  of  two  275-horse-power  boilers  has  a  width  of  24  feet,  the  total  length  of 
the  boiler  house  would  be  143  feet.  The  width  of  the  boiler  house  should  be  50  feet, 
thus  allowing  ample  clearance  for  withdrawing  of  tubes,  etc. 

On  account  of  the  present  popularity  of  turbines  we  will  adopt  them  for  this  plant. 
As  turbines  occupy  a  comparatively  small  floor  space,  the  length  given  for  the  boiler 
plant  is  more  than  necessary  for  the  turbine  room,  and  as  will  be  seen  from  the  plan, 
113  feet  is  all  that  is  required.  Taking  into  consideration  the  removal  of  the  con- 
denser tubes  and  the  dissembling  of  the  turbines  on  the  generating-room  floor,  the 
width  of  the  turbine  room  will  also  be  50  feet.  About  10  feet  of  the  generating  room 
is  set  apart  for  switching  purposes,  offices,  toilets  and  lockers,  etc.,  thus  giving  a  build- 
ing covering  12,800  square  feet,  which  gives  4.28  square  feet  per  K.W.  normal  rating. 
This  figure  is  of  course  liberal,  as  this  is  a  country  power  plant  and  it  is  not  good  prac- 
tice to  crowd  the  plants  as  is  done  in  cities  like  New  York,  Chicago,  etc.,  where  about 
1.5  to  2  square  feet  per  K.W.  is  the  average,  partly  on  account  of  the  boilers  being  installed 
in  two  tiers  and  partly  on  account  of  the  individual  units  being  of  enormous  capacity 


SMALL   POWER  PLANTS.  295 

and  occupying  comparatively  small  floor  space.  The  height  of  the  boiler  room  depends 
upon  the  height  of  the  boilers  themselves  and  also  upon  the  depth  of  the  basement,  if 
one  is  adopted,  while  the  design  of  coal  bunkers  is  also  an  important  controlling  factor. 

There  being  many  advantages  in  having  a  basement,  one  is  therefore  decided'  upon 
for  this  plant,  the  depth  of  which  is  13  feet  from  the  boiler-room  floor  to  the  basement 
floor,  this  giving  about  n  feet  clearance  between  the  basement  floor  and  the  bottom 
of  the  boiler-room  floor  beams. 

Assuming  that  the  boiler  chosen  is  of  the  horizontal  inclined  water-tube  type,  with 
a  total  height  of  18  feet,  and  allowing  the  requisite  space  above  the  boiler  for  smoke 
flue  and  the  steam  piping  leading  from  the  boilers  to  the  main  header,  the  clear  height 
from  the  operating-room  floor  to  the  bottom  of  the  roof  truss  will  be  40  feet.  This 
gives  ample  space  for  the  installation  of  coal  bunkers  above  the  firing  aisle. 

In  deciding  the  height  of  the  generating  room,  the  traveling  crane  and  its  necessary 
clearance  of  the  roof  truss,  and  especially  the  space  required  for  hoisting  the  machinery 
while  erecting  and  dismantling  the  turbines,  have  to  be  taken  into  consideration.  The 
heaviest  part  of  the  750-K.W.  turbines  or  a  i,ooo-K.W.  machine,  which  may  be  the 
future  unit,  may  be  easily  handled  by  a  ten-ton  crane.  As  a  power  crane  is  little  used 
in  this  size  of  plant,  a  hand-operated  crane  is  sufficient.  A  clear  space  of  6  feet  is 
required  from  the  top  of  the  runway  to  the  bottom  of  the  roof  trusses.  The  elevation 
of  the  crane  runway  above  the  operating-room  floor  will  be  24  feet.  This  height  of 
course  depends  entirely  upon  the  type  of  turbine  adopted. 

It  is  assumed  that  a  horizontal  turbine  is  selected.  In  order  to  have  a  proper  con- 
denser arrangement,  the  latter  should  be  placed  directly  below  the  turbine  in  the  base- 
ment, which  will  also  contain  the  condenser  auxiliaries,  piping,  etc.  The  height  of 
this  basement  is  also  13  feet,  giving  a  total  height  from  basement  floor  to  roof  truss  of 
43  feet.  This  arrangement  will  give  the  greatest  convenience,  as  both  boiler-room  and 
turbine^room  floors  are  on  the  same  level. 

As  the  generating  room  and  the  boiler  room  are  of  different  heights,  as  shown  in 
the  cross-section  (Fig.  3),  the  roof  trusses  for  both  rooms  must  be  designed  separately. 
The  extended  crane  columns  at  the  division  wall  will  support  the  inside  ends  of  both 
roofs,  the  pitch  of  the  roof  truss  depending  upon  the  character  of  material  adopted  for 
roofing,  which  in  the  present  case  will  be  reinforced  concrete  covered  with  tar  and 
gravel.  The  pitch  will  therefore  be  one  inch  in  one  foot,  thus  giving  a  height  of  3  feet 
at  the  end  walls  and  8  feet  at  the  partition  wall. 

The  coal  is  brought  to  the  plant  on  the  railroad  siding  and  dumped  into  bins  at 
the  side  of  the  boiler  house.  These  bins  run  the  entire  length  of  the  boiler  house  and 
are  fifteen  feet  wide.  In  order  to  protect  them  from  rain  and  snow,  a  light  corrugated 
iron  awning  is  built  on  a  steel  frame,  all  sides  being  left  open  so  as  not  to  obstruct  the 
natural  light  of  the  boiler  room.  From  here  the  coal  is  brought  into  the  suspended 
coal  bunkers  by  means  of  the  conveyor  system.  At  the  side  of  the  generating  room 
an  area  runs  the  entire  length  of  the  building  in  order  to  give  sufficient  light  and  venti- 
lation to  the  basement.  The  wall  of  this  area,  as  will  be  seen  in  the  cross-section,  acts 
as  a  retaining  wall.  In  order  to  strengthen  this  wall  braces  are  placed  every  16  feet. 


296  STEAM-ELECTRIC   POWER  PLANTS. 

These  braces  are  of  concrete  15  inches  deep  by  8  inches  wide,  reinforced  by  two  f-inch 
rods.     Around  the  top  of  this  wall  is  installed  an  iron  pipe  railing. 

Below  the  basement  floor,  between  the  turbines,  is  a  trench  6  feet  deep  by  4  feet 
6  inches  wide,  containing  the  circulating  water  intake  and  discharge  pipes.  As  the 
main  generating  room  is  divided  by  the  crane  columns  into  16  equal  spaces,  each  about 
1 6  feet,  and  as  about  25  feet  are  required  for  the  switchboard  itself  (four  panels), 
48  feet  in  the  middle  of  the  generating  room  will  be  left  exclusively  for  switching  pur- 
poses, both  in  the  basement  and  on  the  main  operating-room  floor.  As  already  pointed 
out,  the  space  set  apart  for  switching  purposes  is  10  feet  wide.  At  each  side  of  the 
switchboard,  symmetrically  placed,  is  the  main  entrance  adjoining -the  superintendent's 
office  and  the  locker  and  toilet  rooms,  while  below  these  rooms,  respectively,  are 
store-room  and  repair  shop,  and  the  oil  storage  and  filtering  room. 

Location  of  Plant.  —  As  the  plant  runs  condensing  it  is  of  the  utmost  importance 
to  locate  the  building  as  near  to  the  water  edge  as  possible.  Therefore  in  choosing  a 
site  these  two  items  should  be  taken  into  careful  consideration,  namely,  railroad  con- 
nections and  convenient  water  supply.  Further,  the  character  of  the  soil  is  an  impor- 
tant factor  in  the  selection  of  the  site,  as  pile  driving,  excavating,  blasting,  etc.,  should 
not  be  excessive  for  a  plant  of  this  size.  It  is  always  a  paying  practice  to  make  careful 
soundings  and  tests  of  the  soil  before  the  property  is  bought.  Testing  holes  should  be 
driven,  according  to  soil,  some  20  to  30  feet  and  even  deeper.  It  is  important  to  have 
this  work  carried  on  under  skilled  supervision  and  by  one  familiar  with  the  particular 
locality.  Test  loads  may  be  applied  to  determine  the  bearing  power  of  the  soil.  In 
laying  out  the  plant  it  is  important  to  have  the  generating  room  lie  next  to  the  water 
supply  where  possible,  in  order  that  the  condenser  water  intake  may  be  as  short  as 
possible.  Should  the  plant  be  situated  on  a  residential  street  running  parallel  to  the 
river  it  will  be  necessary  to  have  the  generating  room  face  the  street.  It  is  further 
desirable,  where  possible,  to  have  the  generating  room  on  the  north  side  of  the  plant 
in  order  to  have  the  best  light. 

Foundation  Work.  —  If  the  site  contains  quicksand  it  should  either  be  removed 
and  replaced  by  filling,  or  piles  should  be  driven,  upon  which  a  monolithic  concrete 
mat  should  be  laid.  The  latter  is  an  expensive  affair  and  may  be  accomplished  either 
with  wooden  or  concrete  piles.  In  recent  years  it  has  become  common  practice  to 
employ  the  latter,  either  plain  concrete  or  reinforced,  as  they  have  a  comparatively 
greater  carrying  capacity  and  durability,  and,  further,  their  heads  may  extend  far 
above  ground  water.  In  case  wooden  piles  are  used  their  heads  must  be  cut  below 
ground  water  and  thus  deep  excavation  may  be  necessary,  to  which  point  the  founda- 
tions must  be  carried  down.  If  the  soil  should  be  partly  of  rock  and  partly  alluvial, 
the  latter  must  be  carefully  replaced  or  tamped  down  with  layers  of  sand,  each  layer 
being  wetted  before  another  is  applied.  All  rock  must  be  cleaned  before  concrete  is 
applied. 

These  features  being  satisfactorily  accomplished,  the  size  of  the  foundations  fpr 
the  various  machinery  and  the  footings  for  the  building  may  be  determined.  In  cal- 


SMALL  POWER  PLANTS. 


297 


298  STEAM-ELECTRIC   POWER   PLANTS. 

culating  the  foundations  for  the  machinery  as  well  as  for  the  building  walls,  the  weight 
of  the  foundation  itself  must  not  be  overlooked.  The  sizes  of  the  foundations  for  the 
machinery  are  usually  given  in  the  manufacturer's  drawings.  Attention,  however, 
must  be  given  to  secure  the  weight  of  the  machinery,  as  the  particular  condition  of  the 
soil  affects  the  size  of  foundation.  In  figuring  the  foundations  for  boilers  and  other 
similar  apparatus,  it  is  important  to  make  allowance  for  the  water  contained  therein. 
Two  tons  of  total  bearing  load  per  one  square  foot  of  dry  ordinary  sand  is  considered 
an  average  figure.  Each  case,  however,  should  be  treated  separately  and  the  above 
figure  should  not  be  followed  blindly. 

In  specifying  the  mixture  of  concrete,  usually  1:3:6  is  taken  for  machinery  founda- 
tions ;  i  being  first-class  Portland  cement,  3  being  clean,  sharp  sand,  and  6  being  crushed 
bluestone  that  will  pass  through  a  two-inch  mesh. 

Where  anchor  bolts  have  to  be  used  for  securing  machinery,  they  must,  together 
with  the  plates,  be  directly  embedded  in  the  foundation.  Such  bolts  are  required  for 
the  footings  of  the  boiler  and  building  columns  and  the  various  auxiliary  machinery. 
The  turbine  itself  does  not  need  anchor  bolts.  At  least  one-half  inch  should  be  allowed 
for  grouting  after  the  material  has  been  placed.  The  concrete  forms  for  duplicate 
machinery  may  be  used  repeatedly.  In  placing  the  concrete  it  should  not  be  allowed 
to  fall  more  than  8  to  10  feet,  as  there  is  liability  of  the  stones  becoming  separated  from 
the  cement  and  being  surrounded  with  water,  thus  giving  a  poor  bond.  In  addition  to 
this  the  concrete  should  be  tamped. 

Should  the  building  be  located  where  concrete  is  difficult  to  obtain  and  where  first- 
class  brick  is  at  hand,  these  bricks  should  be  of  hard-burned  clay  laid  in  thin  layers  of 
high-grade  hydraulic  cement.  The  foundation  of  the  building,  if  located  below  ground 
water  level,  should  be  provided  with  some  sort  of  waterproofing.  The  footings  of 
boiler  and  wall  columns  should  lie  below  or  flush  with  the  basement  floor.  Attention 
will  be  called  to  the  fact  that  frequently  these  footings  are  extended  some  3  or  4  feet 
above  the  floor  level,  which  is  much  more  expensive  than  running  the  steel  columns 
down  to  the  floor  level,  and  has  the  further  disadvantages  of  being  always  an  obstruc- 
tion, giving  many  corners  for  the  accumulation  of  dirt.  Under  these  conditions  it  is 
difficult  to  run  circulating  water  pipes,  drain  pipes,  etc.,  at  the  floor  level  along  the 
building  wall. 

Superstructure.  —  The  superstructure  of  the  power  plant  should  be  as  simple  as 
possible,  yet  pleasing  in  appearance.  Fireproof  is  one  of  the  first  considerations,  and 
this  is  best  obtainable  by  adopting  a  skeleton  steel  structure  with  concrete  or  brick 
walls.  The  roof,  windows,  doors,  etc.,  should  also  be  of  fireproof  material.  The  latter 
two  items  are  frequently  neglected  in  plants  of  the  capacity  here  described. 

As  to  whether  a  steel  skeleton  building  should  be  adopted,  the  following  items  will 
be  considered:  The  first  cost  of  such  a  building  is  a  small  percentage  more  than  that 
of  a  common  brick  or  concrete  building,  when  the  latter  has  to  carry  steel  roof  trusses, 
crane  runways,  etc.,  but  far  greater  rigidity  is  obtained.  The  installation  of  suspended 
coal  bunkers,  the  connection  of  floor  frames,  platforms,  galleries,  etc.,  are  much  more 


SMALL  POWER  PLANTS.  299 

easily  accomplished  in  a  steel  building.  Pipe  supports  and  anchors  are  easily  arranged. 
By  using  a  steel  skeleton  the  thickness  of  the  building  walls  will  be  reduced  about  fifty 
per  cent.  With  this  type  of  building  when  brick  is  used  13  inches  thickness  will  be 
sufficient  for  the  walls.  In  monolithic  concrete  walls  reinforced  with  "expanded 
metal"  or  "wire  cloth,"  a  thickness  of  from  6  to  8  inches  will  be  sufficient,  provided 
that  these  walls  do  not,  as  frequently  happens,  act  as  retaining  walls.  This  part  of 
the  wall,  however,  must  be  thicker  according  to  the  pressure  of  the  soil.  Pilasters  are 
required  to  enclose  the  steel  columns,  which  are  set  half  in  the  walls,  thus  at  the  same 
time  giving  a  possibility  for  artistic  design.  In  some  localities,  especially  in  tropical 
zones,  it  may  be  advisable  to  use  corrugated  iron  in  place  of  brick  or  concrete,  on 
account  of  the  frequent  shocks  and  earthquakes.  In  this  case  it  will  be  best  to  build 
all  walls  as  well  as  the  roof  of  the  same  material.  This  type  of  building,  however, 
requires  frequent  painting  and  repairs,  and  is  not  pleasing  to  look  upon. 

The  steel  skeleton  for  the  building  may  be  either  of  the  self-supporting  type,  in 
which  case  light  curtain  walls  are  used,  or  the  walls  may  be  self-supporting  and  carry 
the  steel  work.  When  designing  the  steel  work  proper  care  should  be  taken  to  secure 
thorough  bonding  of  the  steel  work  and  the  walls.  The  entire  building  column  may 
be  enclosed  in  a  pilaster  or  only  a  part  of  it,  depending  largely  upon  the  choice  of  build- 
ing material.  Brick  or  monolithic  concrete  may  easily  partly  or  completely  enclose 
the  building  columns,  while  in  the  use  of  the  hollow  concrete  block  it  is  desirable  to 
have  as  few  specially  designed  blocks  as  possible,  and  it  is,  therefore,  important  that 
the  building  columns  do  not  break  the  inside  lines  of  the  walls.  Anchorages  may  be 
secured  by  placing  light  rods  on  the  extended  flanges  of  the  columns  and  bonding 
them  between  the  concrete  1: locks.  The  various  steel  columns  should  always  be  of 
the  open  type  and  of  simple  design,  so  as  to  secure  easy  access  for  painting  and 
inspection.  Cross  or  X  bracing  is  frequently  found  between  the  boiler  columns  in  the 
basement,  but  this  practice  is  employed  only  by  steel  constructors  unfamiliar  with 
power-house  operation. 

In  designing  the  floors  of  the  boiler  and  generating  rooms  a  load  factor  of  250 
pounds  per  square  foot  may  be  employed,  as  the  entire  weight  of  all  machinery  is  car- 
ried by  the  foundations,  which  are  built  up  from  the  basement  floor.  This  load  factor 
may  also  be  applied  to  the  switching-room  floor,  etc.  Sufficient  and  conveniently 
located  stairways  should  be  provided.  Care,  however,  must  be  exercised  that  they 
do  not  block  up  passages  required  for  the  easy  operation  of  the  plant.  As  the  con- 
densers and  various  pumps  are  located  in  the  basement,  it  is  good  practice  to  provide 
at  least  one  large  opening  in  the  floor  in  order  to  facilitate  removal  of  the  machinery 
by  means  of  the  overhead  traveling  crane.  This  opening  at  the  same  time  will  give 
additional  light  and  ventilation  for  the  basement.  In  the  case  under  consideration 
this  opening  will  be  located  between  turbines  in  front  of  the  exciter  units  in  the  middle 
of  the  plant. 

In  the  spacing  of  the  crane  columns  care  must  be  taken  in  order  to  secure  equal 
spaces  and  symmetry  in  the  window  arrangement.  As  the  building  is  113  feet  long, 
seven  bays  of  about  16  feet  each  will  make  'a  good  layout  and  at  the  same  time  an 


300  STEAM-ELECTRIC   POWER   PLANTS. 

economical  crane  run- way  construction.  As  the  crane  capacity  is  ten  tons,  1 8- inch 
beams  are  required  for  the  crane  runway. 

It  is  common  practice  with  water-tube  boilers  to  suspend  them  on  steel  structures, 
which  are  furnished  with  the  boilers.  As,  however,  an  overhead  coal  bunker  is  to  be 
installed,  these  front  columns  must  be  replaced  by  heavier  ones. 

In  the  power  plant  in  question  it  is  necessary  to  install  two  groups  of  boiler- 
bunkers,  one  on  each  side  of  the  chimney,  one  for  each.  These  bunkers  have 
V- shaped  bottoms  in  order  properly  to  empty.  They  have  a  capacity  of  five  tons  per 
running  foot  and  are  made  up  of  ^-inch  or  f -inch  material,  provided  at  the  bottom 
with  cast-iron  outlets,  to  which  arc  connected  the  coal  "down  takes"  to  the  boilers. 

The  roof  truss  has  beerj  touched  upon  in  determining  the  height  of  the  building; 
it  remains,  however,  to  go  more  into  detail.  Provision  has  to  be  made  for  chimney, 
exhaust  pipes  and  vent  pipes,  etc.,  all  of  which  must  be  provided  with  collars,  and 
after  the  pipes  have  been  erected,  rain  hoods  must  be  installed.  Four  ventilating 
hoods  should  also  be  provided  on  the  roof  of  the  boiler  room,  but  for  the  generating 
room  such  ventilators  are  not  required,  and  are  undesirable,  as  they  are  liable  to  leak, 
and  a  small  leak  may  result  in  a  serious  shut-down  of  the  plant.  From  the  top  of  the 
coal  bunker  to  the  roof  itself  a  light  plastered  wall  will  serve  to  keep  the  dust  from  the 
boiler  operating  room.  On  one  side  of  this  enclosed  coal-bunker  room  an  iron  grate 
walk  will  provide  easy  access  to  the  coal  conveyor  system.  Steel  stairs  and  bridges 
will  be  installed  between  the  boiler  batteries,  while  short  ladders  from  the  boiler  room 
will  give  access  to  the  coal  bunkers.  In  front  of  the  chimney,  between  the  boilers, 
and  some  8  feet  above  the  operating-room  floor,  is  erected,  on  steel  columns,  a  platform 
12  feet  square,  on  which  are  placed  a  "make-up"  tank,  the  purpose  of  which  will  be 
seen  later,  and  two  feed-water  heaters,  only  one  of  which  is  placed  for  the  present 
equipment.  Stairways  lead  up  to  the  platform  and  from  here  to  the  top  of  the  boilers. 

Masonry  Work,  etc.  —  If  brick  of  a  good  quality  is  cheap  in  the  locality  where  the 
plant  is  erected  it  will  be  wise  to  use  this  material;  12-  to  1 3-inch  walls,  with  pilasters 
some  4  feet  wide  by  4  to  8  inches  deep  will  be  sufficient  for  the  walls  in  the  present 
case.  The  wall  in  the  basement  must  be  correspondingly  heavier,  depending,  of  course, 
as  already  pointed  out,  on  whether  it  acts  as  a  retaining  wall  or  not.  Window  and  door 
sills  and  lintels  should  be  of  granite  or  concrete  blocks,  as  also  should  be  the  coping, 
the  latter  being  6  inches  thick. 

Adopting  the  most  modern  practice  in  engineering  under  ordinary  circumstances 
for  this  particular  building,  the  entire  walls,  floors  and  roof  should  be  monolithic  con- 
crete, reinforced  partly  with  iron  and  "expanded  metal,"  or  it  may  be  the  so-called 
"wire  cloth."  In  this  type  of  construction,  first  of  all,  skilled  carpenters  are  required 
for  making  the  forms,  which  skill  is  measured  by  the  ability  to  build  a  form  which  may 
be  easily  put  together  and  taken  down,  as  each  form  may  be  used  from  twenty  to  thirty 
times  and  even  more  before  the  building  is  completed.  Further,  skilled  supervision 
is  necessary  in  order  that  the  concrete  shall  be  properly  mixed  and  the  expanded  metal 
properly  placed,  also  that  the  concrete  may  be  well  tamped  into  place.  The  mixture 
of  concrete  being  1:2:4,  four  being  trap  rock  passing  through  a  one  and  one-half  inch 


SMALL  POWER  PLANTS. 


301 


CA3 


fO 

6 


302  STEAM-ELECTRIC   POWER   PLANTS. 

mesh,  and  the  stone  must  be  worked  away  from  the  form  in  order  to  obtain  a  smooth 
surface.  The  basement  walls,  whose  mixture  of  concrete  is  1:3:6,  do  not  require  any 
reinforcement  other  than  some  three  f-inch  rods  embedded  in  the  lintels  of  the  doors 
and  windows.  The  walls  above  the  operating-room  floor  will  be  8  inches  thick  and 
will  contain  one  layer  of  expanded  metal,  three- inch  No.  10,  which  is  so  placed 
that  at  both  the  vertical  as  well  as  the  horizontal  joints  the  expanded  metal  is  over- 
lapped one  foot.  It  must  be  properly  secured  to  the  columns.  The  lintels  in  the 
doors  and  windows  will  contain  f-inch  rods,  similar  to  those  in  the  basement,  in 
addition  to  the  expanded  metal. 

All  floors  for  boiler  room,  engine  room,  etc.,  must  be  designed  for  a  uniform  load 
of  250  pounds  per  square  foot,  the  beams  being  located  5  inches  below  the  floor  level,  this 
space  being  filled  with  concrete  reinforced  with  one  layer  of  expanded  metal,  six-inch 
No.  4.  The  size  of  floor  beams,  of  course,  depends  upon  the  spacing,  and  the  distance 
between  them  should  not  be  more  than  6  feet.  Much  care  should  be  exercised  to 
properly  locate  all  holes  in  the  floor  for  pipes,  etc.,  in  order  to  avoid  unnecessary  cutting 
of  the  floor  and  expanded  metal.  These  holes  should  be  provided  with  cast-iron 
thimbles  in  order  to  secure  a  proper  finish. 

The  roof  will  be  made  of  a  layer  of  three  and  one-half  inch  concrete  reinforced  with 
expanded  metal,  three-inch  No.  10.  This  roof  may  be  made  up  of  reinforced  con- 
crete slabs  made  on  the  ground  and  hoisted  up  into  place,  or,  preferably,  of  one  mono- 
lithic mass.  After  this  is  finished  the  roof  will  be  asphalted  and  graveled.  Also,  care 
must  be  taken  here  in  locating  all  openings  for  exhaust  pipes,  vents,  etc.,  and  light  iron 
thimbles  should  be  installed  around  the  chimney  and  the  various  pipe  openings. 

Each  roof  will  be  provided  with  two  five-inch  leaders  run  on  the  inside  of  the  build- 
ing wall  in  order  to  protect  them  from  frost.  These  leaders  should  be  run  as  incon- 
spicuously as  possible  and  away  from  all  electric  apparatus.  This  latter  precaution 
must  be  taken  not  only  on  account  of  the  liability  of  leakage,  but  as  the  difference  in 
temperature  between  the  inside  and  the  outside  of  the  pipe  may  collect  water  which, 
dropping  upon  the  electric  apparatus,  may  result  in  a  serious  shut-down.  In  fact, 
frequent .  short  circuits  occurring  from  this  cause  have  proven  very  difficult  to  locate. 

Sanitary  and  Architectural  Features. —  Much  attention  may  profitably  be  devoted 
to  the  sanitary  features  of  the  design.  Cleanliness  is  one  of  the  most  important  factors 
in  the  successful  operation  of  a  plant,  resulting  in  more  ease  in  obtaining  first-class 
workmen,  raising  the  general  moral  tone  of  the  men  and  fostering  general  satisfaction 
among  the  employees. 

The  floors  in  the  generating  room,  in  the  basement,  will  be  provided  with  proper 
drainage  by  giving  them  a  slight  pitch  toward  the  circulating  water  trench  which  is 
covered  with  perforated  iron  and  connected  to  the  sewerage  system.  Where  this  is 
undesirable  the  drainage  may  be  accomplished  by  the  installation  of  several  twelve- 
inch  by  twelve-inch  sumps  interconnected  by  a  three-  or  four-inch  tile  pipe.  On 
account  of  the  large  amount  of  water  dripping  down  from  the  ash  hoppers  there  will 
be  a  trough  in  the  basement  floor  of  the  boiler  room  running  the  entire  length  of  the 


SMALL  POWER  PLANTS.  303 

boiler  room,  draining  into  a  collecting  basement.  The  rest  of  the  boiler-house  base- 
ment floor  will  be  pitched  toward  this  trench.  As  already  pointed  out,  column  founda- 
tions above  the  floor  level  should  be  avoided  as  much  as  possible.  The  drainage  from 
the  roofs  and  the  waste  pipes  from  the  plumbing  fixtures  may  be  easily  emptied  into 
the  main  sewer  or  the  river. 

The  toilet  facilities  should  consist  of  two  closets,  three  urinals,  two  enameled  iron 
wash  basins  and  one  galvanized  iron  sink.  At  one  side  of  the  toilet  room  there  should 
be  two  shower  baths.  Each  shower-bath  compartment  should  be  divided  so  as  to 
serve  for  dressing  also.  Open  plumbing  should  be  used  exclusively  and  walls  and 
floors  should  be  of  white  tile.  White  or  light  color  is  chosen  for  the  toilet  room  in  order 
to  make  dirt  conspicuous.  The  locker  room  will  be  cut  off  from  the  toilet  by  a  parti- 
tion wall.  This  room  will  contain  some  dozen  lockers  eighteen  inches  by  twenty-four 
inches  and  about  six  feet  high.  They  will  be  constructed  of  wire  netting  mounted  on 
light  angle- iron  frames.  As  the  toilet  and  locker  rooms  are  located  on  the  main  floor 
of  the  generating  room  on  the  side  farthest  from  the  boiler  room  it  may  be  reached 
from  the  latter  by  passing  through  the  basement  and  up  a  flight  of  stairs  directly  into 
the  locker  room.  In  the  office  of  the  superintendent  there  will  be  placed  one  open 
plumbing  wash  bowl  of  white  porcelain,  with  a  toilet  cabinet. 

Proper  means  of  ventilation  for  the  boiler  room  will  be  secured  by  mounting  four 
ventilating  hoods  in  the  roof,  while  sections  of  the  main  windows  are  arranged  for 
opening  on  hinges.  A  number  of  small  windows  opening  on  the  generating-room 
roof,  combined  with  the  lower  windows  on  the  opposite  side  of  the  room,  will  assure  an 
excellent  natural  ventilation.  Windows  are  also  provided  above  the  coal  bunkers,  as 
will  be  seen  in  the  cross-section.  (Fig.  3.) 

The  roof  of  the  generating  room  will  not  be  provided  with  these  hoods,  as  such 
devices  or  louvers  are  liable  to  leak,  resulting  in  serious  interruption  of  the  service. 
For  the  same  reason  the  windows  in  the  switching  room  are  so  designed  that  they 
cannot  be  opened,  while  all  other  windows,  especially  the  large  ones  in  the  end  walls, 
are  arranged  to  swing  open  on  a  horizontal  axis. 

The  architectural  features  of  a  power  plant  are  usually  grossly  neglected,  and  it  is 
the  opinion  of  the  author  that  it  costs  practically  no  more  to  create  a  well-designed, 
pleasant-looking  building  than  a  simple,  plain  structure  with  windows  and  doors 
arranged  entirely  out  of  harmony.  If  the  power  plant  is  located  in  a  manufacturing 
district  the  structure  should  be  of  such  a  design  as  to  give  relief  to  the  eye,  but  where 
the  building  is  in  a  residential  section  it  should  at  least  harmonize  with  the  architecture 
of  the  neighborhood. 

As  the  building  is  made  of  reinforced  concrete,  the  forms  should  be  designed  as 
simply  as  possible.  Therefore  all  window  and  door  sills  will  be  straight,  while  the 
water  tables,  pilasters  and  cornices  will  be  all  of  straight  pattern,  as  shown  in  the  ele- 
vations. (Fig.  i.) 

The  pilasters,  window  and  door  lintels  are  well  projected  beyond  the  building-line, 
while  prominent  cornices  will  finish  the  building.  This  will  harmonize  with  the  tall 
chimney,  also  of  concrete,  rising  practically  from  the  middle  of  the  building.  The 


STEAM-ELECTRIC   POWER   PLANTS. 


entire    building   is   finished  with  a  cement 
wash  in  order  to  give  a  uniform  color. 

It  is  of  equal  importance  to  look  for  a 
pleasing  interior  appearance  of  the  plant. 
The  first  thing  attracting  the  attention  is  a 
good  general  layout  and  general  arrange- 
ment of  the  main  prime  movers  on  the 
operating-room  floor.  In  the  plant  under 
consideration  the  turbines  are  arranged 
two  on  each  side  of  the  plant,  while 
the  two  exciter  units  are  arranged  directly 
in  the  middle  of  the  plant.  In  front 
of  these  is  the  stairway  leading  to  the 
basement.  For  the  sake  of  appearance 
the  turbines  are  chosen,  two  right  hand 
and  two  left  hand  as  will  be  noticed  in 
the  plan  (Fig.  2).  The  exciter  units  are 
chosen  in  the  same  manner.  Besides  this 
the  steam  ends  of  the  turbines  are  placed 
end  to  end  in  the  center  of  the  room.  All 
piping  is  carried  below  the  floor,  thus 
avoiding  the  objectionable  appearance  of 
exposed  piping.  The  floors  themselves 
are  covered  with  light  gray-colored  tiles, 
while  the  walls  of  the  generating  room, 
for  a  height  of  some  six  feet,  are  also 
finished  in  cream-colored  glazed  tile.  A 
brown  border  will  finish  the  wainscoting, 
thus  giving  a  pleasing  contrast  to  the 
whitewashed  walls.  All  steel  work,  such 
as  columns,  roof  trusses,  traveling  cranes, 
etc.,  have  a  uniform  green  color.  The 
windows  themselves  are  well  arranged  and 
symmetrically  placed  with  regard  to  the 
columns,  while  the  switchboard  will  be,  ac- 
cording to  American  practice,  of  enameled 
slate.  The  apparatus  itself  is  well  arranged 
upon  the  various  panels  in  order  to  secure 
as  perfect  symmetry  as  possible.  While 
it  may  seem  extravagant  at  first  thought 
to  finish  the  floors  and  walls  in  tile,  this  is 
a  comparatively  small  item  of  the  total  cost 
of  the  plant,  has  always  been  considered 


SMALL  POWER  PLANTS.  305 

standard  practice  in  Continental  design  and,  in  fact,  is  being  adopted  by  American 
engineers  as  the  best  policy. 

Coal  and  Ash  Handling  Systems.  —  As  already  mentioned  a  raiiroad  siding  is 
brought  alongside  the  boiler  house.  The  cars  are  brought  up  a  small  incline  above 
the  coal  bins  extending  the  entire  length  of  the  boiler  house.  These  bins  are  divided 
into  nine  compartments  corresponding  to  the  placing  of  the  building  columns.  As 
will  be  seen  in  the  accompanying  illustration,  these  bin  floors  have  a  slope  of  forty 
degrees  toward  the  boiler  house  and  empty  through  chutes  to  the  coal  conveyor  below 
the  basement  of  the  boiler  room.  The  advantage  in  dividing  up  these  bins  is  that  the 
coal  may  be  stored  according  to  grade.  Directly  at  the  first  bin  a  scale  is  provided  in 
order  to  keep  accurate  account  of  the  coal  supply.  A  bucket  conveying  system  is 
designed  for  running  below  the  basement  floor  of  the  boiler  room,  up  the  end  wall, 
over  the  entire  length  of  the  coal  bunkers  and  down  the  other  end  wall,  thus  forming  a 
complete  endless  chain.  The  vertical  sections  of  this  system  on  both  end  walls,  for 
the  sake  of  appearance  and  to  avoid  accident,  are  encased  in  sheet-iron  shafts.  The 
bucket  coal  conveyor  system  with  a  maximum  speed  of  fifty  feet  per  minute  will  be 
operated  by  a  15 -horse-power,  three-phase,  220- volt  induction  motor.  A  tripping 
device  is  placed  on  the  running  rail  of  the  conveyor  system  above  the  coal  bunkers, 
thus  enabling  the  operator  to  discharge  the  coal  in  any  one  of  the  suspended  bunkers. 
The  suspended  coal  bunkers  are  designed  for  a  coal  storage  capacity  of  five  tons  per 
running  foot,  and  are  suspended  from  girders  running  from  column  to  column.  The 
total  coal  storage  capacity  in  the  suspended  bunkers  will  be  about  480  tons,  which  will 
be  sufficient  to  run  the  eight  275-horse-power  boilers  for  eleven  days,  figured  on  a  basis 
of  four  pounds  per  boiler  horse-power  hour  for  twenty-four  hours'  continuous  opera- 
tion. This  figure,  of  course,  depends  largely  upon  the  grade  of  coal  used  and  upon 
the  system  of  firing.  Besides  the  above  coal  storage  capacity  a  still  greater  capacity 
is  obtained  in  the  bins  at  the  side  of  the  boiler  room,  where  some  540  tons  will  be  stored, 
thus  giving  a  total  coal  storage  capacity  of  over  1,000  tons. 

As  already  mentioned,  all  coal  brought  into  the  plant  is  weighed  on  a  track  scale, 
while  no  provision  is  made  for  measuring  the  coal  dropping  from  the  suspended  bunk- 
ers to  the  hoppers  of  the  mechanical  stokers.  The  reasons  for  this  design  are  as 
follows:  weighing  the  coal  at  the  stoker  hoppers  would  necessitate  the  crushing  of  the 
coal  before  it  was  deposited  into  the  suspended  bunkers  which  would  require  a  crusher 
for  each  of  the  nine  bins,  unless  the  coal,  as  delivered,  was  small  enough  not  to  clog 
these  scales.  In  addition  to  these  crushers,  mechanically  operated  screens  would  have 
to  be  installed  so  as  to  make  it  impossible  for  large  lumps  to  enter  the  scale.  Where, 
however,  small-size  anthracite  is  used  exclusively,  crushers  are  not  necessary  and  sus- 
pended bunker  scales  may  be  advantageously  employed.  Although  the  writer  is  very 
much  in  favor  of  keeping  close  record  of  the  coal  consumed  in  each  furnace,  when 
large-sized  coal  is  burned  it  may  be  weighed  in  the  railroad  car,  dumped  into  one  empty 
coal  bin,  from  there  conveyed  to  an  empty  coal  bunker  and  fed  to  the  boilers.  It  must, 
however,  be  remembered  that  when  large-sized  coal  is  burned,  whether  it  is  anthracite 


306  STEAM-ELECTRIC   POWER   PLANTS. 

or  bituminous,  it  must  easily  pass  through  the  coal  down-takes  to  the  boilers.  The 
down-take  is  a  cast-iron  pipe  sixteen  inches  in  diameter  and  is  provided  at  the  bottom 
of  the  bunker  with  a  gate  operated  from  the  main  floor  by  means  of  a  chain. 

The  ashes  are  carried  away  by  the  above-described  conveying  system,  as  will  be  seen 
from  the  accompanying  illustration.  A  large  ash  hopper  will  be  installed  under  each 
boiler,  constructed  of  structural  steel  and  masonry  work.  Chutes  similar  to  those  on 
the  coal  bins  will  be  installed  on  these  ash  hoppers  and  will  also  be  provided  with  cut- 
off gates,  so  that  when  coal  is  being  conveyed  the  ashes  may  be  held  in  the  hoppers. 
After  the  ashes  are  received  in  the  conveyor  they  may  be  dumped  into  the  main  ash 
hopper  above  the  boiler-room  floor  occupying  the  23-foot  by  iQ-foot  space  in  front  of 
the  chimney,  between  the  suspended  coal  bunkers.  From  this  main  ash  hopper  a 
spout  runs  through  the  boiler-room  wall  so  as  to  empty  the  ashes  into  the  empty  coal 
car.  The  capacity  of  the  suspended  ash  hopper  is  greater  than  that  of  one  standard 
coal  car,  and  assuming  the  volume  of  ash  to  be  about  10  per  cent  of  the  coal  burned, 
one  car  of  ashes  must  be  removed  for  every  ten  cars  of  coal  delivered. 

As  the  ashes  are  frequently  wet  in  the  boiler  ash  hoppers  and  as  it  is  important  that 
the  water  be  not  carried  along  in  the  conveyor  system,  a  drainage  trench  has  been 
arranged  in  front  of  the  boiler  columns,  as  will  be  noticed  in  the  accompanying  cross- 
section  (Fig.  3). 

In  order  to  remove  the  collection  of  soot  from  the  boilers,  a  special  cast-iron  hopper 
is  connected  directly  to  the  ash  hopper.  The  soot  will  discharge  from  here  through 
the  ash  hopper  and  will  be  carried  away  in  the  conveyor  with  the  ashes.  Special  pre- 
caution must  be  taken  to  keep  the  gate  in  the  soot  hopper  as  tight  as  possible  in  order 
that  no  air  may  enter  the  boiler  at  this  point,  as  this  would  reduce  the  efficiency  of  the 
boiler  plant. 

Boilers,  etc.  —  As  already  pointed  out  the  boilers  are  arranged  in  one  row,  two  in 
a  battery.  The  boilers  are  designed  for  a  working  pressure  of  200  pounds.  Each 
boiler  consists  of  two  main  steam  drums  and  a  number  of  inclined  water  tubes,  the 
whole  being  suspended  from  two  pairs  of  beams  supported  by  steel  columns.  The 
boiler  walls  themselves  are  carried  on  structural  steel  also  partly  supported  by 
the  above-mentioned  columns. 

As  the  boilers  have  a  heating  surface  of  2,750  square  feet,  about  fifty-six  square  feet 
of  grate  surface  is  required,  assuming  that  anthracite  of  about  1,250  to  1,350  British 
thermal  units  per  pound  is  used.  As  the  plant  is  located  where  skilled  labor  is  diffi- 
cult to  obtain,  over-feed  mechanical  stokers  (steam  driven)  will  be  installed,  and  may 
be  either  of  the  chain  grate  or  inclined  type.  Between  the  water  tubes  and  the  drums 
will  be  inserted  a  superheater  capable  of  raising  the  temperature  of  steam,  at  175 
pounds  pressure,  150°  Fahr. 

Between  the  upper  row  of  water  tubes  and  the  superheater  is  a  fire-brick  partition 
with  a  damper  so  placed  that  the  gases  may  pass  either  through  the  superheater  or 
below  the  partition,  thus  in  case  of  emergency  allowing  the  superheater  to  be  cut  off 
and  thus  protected  from  excessive  heat.  It  will,  therefore,  be  seen  that  if  the  superheater 


SMALL  POWER  PLANTS.  307 

should  be  damaged  by  the  negligence  of  the  operators  it  will  still  be  easily  possible  to 
operate  the  boiler,  supplying  saturated  steam,  as  proper  means  have  been  made  for 
by-passing  the  superheater. 

Each  boiler  is  provided  with  two  2^-inch  blow-offs,  connected  to  a  3-inch  main  pipe 
which  discharges  into  a  blow-off  tank,  4  feet  in  diameter  and  5  feet  high.  At  the  boiler 
each  blow-off  pipe  is  provided  with  a  blow-off  cock  and  an  additional  cut-off  valve, 
controlled  from  the  main  operating-room  floor.  The  blow-off  piping  and  the  blow- 
off  tank  itself  are  located  in  the  basement.  The  tank  is  provided  with  a  vent  con- 
nected to  the  atmospheric  exhaust  pipe  and  a  drain  pipe  emptying  into  the  sewer 
system.  Each  boiler  is  provided  with  two  safety  valves  mounted  on  the  cross-over 
piece  connecting  the  two  drums.  The  necessary  gauges  and  water  columns  will  be 
installed  for  each  boiler. 

Boiler  Feed-Water  Supply.  — The  make-up  tank,  as  already  stated,  is  located  in 
the  boiler  room  on  a  platform  some  eight  feet  above  the  floor  level.  It  is  six  feet  in 
diameter  and  seven  feet  high,  and  will  receive  all  the  water  from  the  condensers  and  the 
house  pumps,  and  is  provided  with  an  overflow.  In  case  the  condenser  fails  to  work 
properly  and  no  water  is  supplied  by  the  hot  well  pumps,  the  house  pumps  will  not  be 
sufficient  to  furnish  the  entire  supply  and  a  five-inch  city  main  connection  is,  therefore, 
provided  for  the  make-up  tank.  Where  this  cannot  be  secured  the  boiler  feed  pumps 
have  to  draw  their  water  directly  from  the  circulating  water  pipes  or  from  some  other 
source,  such  as  a  well.  Under  ordinary  conditions  the  boiler  feed  pump  draws  its 
water  from  the  make-up  tank  and  pumps  it  through  the  heater,  which  is  mounted 
upon  the  platform,  to  the  boiler.  With  the  original  equipment  only  one  closed  heater 
is  installed  receiving  the  exhaust  from  all  the  auxiliary  machinery,  by  means  of  which 
a  feed- water  temperature  of  180°  to  200°  Fahr.  is  obtainable. 

Two  boiler  feed  pumps  will  be  installed,  each  having  a  capacity  of  550  gallons  per 
hour,  running  at  low  speed,  this  being  sufficient  to  supply  four  boilers,  assuming  40 
pounds  of  water  per  boiler  horse-power.  This  apparently  excessive  pump  capacity 
is  chosen  because  after  the  pump  has  been  in  operation  for  some  time,  on  account  of 
the  wear  on  the  plunger,  etc.,  the  supply  will  not  be  quite  up  to  the  full  rated  capacity. 
The  type  of  pump  adopted  for  this  purpose  has  four  single-acting  plungers  of  4j-inch 
diameter  and  8-inch  stroke,  while  the  steam  cylinders  are  6  inches  in  diameter,  the 
steam  connections  being  ij  inches  and  exhaust  2  inches. 

The  main  boiler  feed  piping  runs  above  the  boiler  drums  suspended  from  the  boiler 
and  coal  bunker  columns.  From  here  2^-inch  pipes  lead  to  the  boiler  drums.  These 
latter  pipes  are  provided  with  a  check  valve  placed  between  two  globe  cut-off  valves. 
In  the  steam  pipe  near  the  feed  pump  is  inserted  a  pressure  regulator  connected  to  the 
main  boiler  feed  pipe  by  means  of  a  small  pipe  in  order  to  automatically  control  the 
supply  of  boiler  feed  water. 

The  return  of  the  hot  well  pumps,  all  exhaust  pipes  of  the  auxiliary  machinery 
leading  to  the  heater,  the  heater  itself  and  the  boiler  feed- water  pipes  are  covered  with 
85  per  cent  asbestos  —  magnesia. 


308  STEAM-ELECTRIC  POWER  PLANTS. 

Flues  and  Smokestack.  —  In  order  that  the  space  between  the  rear  of  the  boilers 
and  the  division  wall  should  not  be  made  excessively  wide  the  smoke  flue  is  run  above 
the  boilers,  since  on  account  of  the  installation  of  the  suspended  coal  bunkers  there  was 
ample  space  for  this  design.  As  will  be  seen  in  the  cross-section  (Fig.  3)  the  indi- 
vidual boiler  breechings  are  carried  straight  up  into  the  main  flue.  As  the  breeching 
has  a  sectional  area  of  8.5  square  feet  (0.31  square  feet  per  boiler  horse-power)  and 
extends  some  distance  in  back  of  the  drums,  it  will  be  noticed  that  sufficient  space  is 
left  for  reaching  the  manhole.  The  smoke  flue  itself  is  carried  on  structural  steel 
supported  partly  on  the  division  wall  and  partly  on  beams  suspending  the  boiler.  The 
expansion  of  the  main  smoke  flue  amounts  to  approximately  2  inches.  An  expansion 
joint  has  been  placed  between  boilers  No.  2  and  No.  3.  As  the  plant  is  not  completed 
on  the  other  side  of  the  stack,  no  expansion  joint  is  installed  there.  The  expansion 
joint  is  of  the  sliding  sleeve  type  with  bolts  and  slots.  Attention  must  be  called  to  the 
fact  that  this  joint  must  be  made  as  nearly  air-tight  as  practicable,  as  any  leakage  here 
will  materially  decrease  the  draft  below  the  furnace.  The  cross-section  of  each  main 
flue  is  36  square  feet  with  arched  top,  the  flue  itself  being  made  up  of  ^-inch  rolled 
plates  reinforced  by  2\  X  2\  X  \  inch  angles.  Cleaning  doors  are  provided  at  the 
end  of  each  floor  for  removing  soot. 

The  amount  of  draft  is  regulated  automatically  by  means  of  dampers  placed  in 
the  breeching  of  each  boiler.  The  main  flues  are  not  provided  with  dampers,  there- 
fore one  damper  regulator  is  depended  upon  for  operating  the  entire  plant,  the  above- 
mentioned  dampers  being  connected  by  one  common  rod  which  is  operated  by  the 
regulator  located  between  boilers  Nos.  4  and  5. 

The  total  ultimate  capacity  of  the  boiler  plant  will  be  2,200  horse-power,  and  assum- 
ing a  coal  consumption  of  four  pounds  per  boiler  horse-power,  the  height  of  the  chimney 
will  be  175  feet  and  the  diameter  8  feet  according  to  Kent's  table.  As  there  are  two 
smoke  flues  it  is  necessary  to  erect  a  deflecting  wall  up  to  some  2  feet  above  the  smoke 
flues.  The  chimney  itself  is  made  of  reinforced  concrete  having  an  inner  and  an  outer 
shell,  the  former  going  up  only  to  a  point  about  30  feet  above  the  entrance.  This  inner 
shell  has  a  thickness  of  5  inches  while  the  outer  shell  up  to  this  same  height  is  7  inches 
thick.  Between  the  two  shells  is  an  air  space  of  4  inches.  The  remainder  of  the 
chimney  is  constructed  with  a  single  shell  5  inches  thick.  Both  shells  are  reinforced 
vertically  as  well  as  horizontally  by  iron  rods  or  small  T-irons,  the  mixture  of  concrete 
being  one  part  cement  to  four  parts  sand,  no  crushed  stone  being  employed  except  for 
the  base. 

The  chimney  is  properly  protected  by  a  lightning  rod  and  provided  with  iron  rungs 
on  the  outside,  giving  access  to  the  top.  It  is  frequently  claimed,  especially  by  con- 
crete chimney  builders,  that  rungs  are  not  required  with  this  kind  of  chimney;  the  author 
is  of  the  opinion,  however,  that  they  are  very  essential,  and  as  it  is  difficult  to  place 
them  in  a  4-inch  concrete  wall,  especially  when  forms  have  to  be  removed  and  replaced, 
he  would  suggest  the  use  of  rungs,  in  the  form  of  a  rectangle  extending  through  the 
chimney  shell  and  forming  steps  inside  and  outside.  At  the  base  of  the  chimney  a 
clean-out  door  is  provided. 


SMALL  POWER  PLANTS.  309 

Steam  Piping.  —  In  order  to  draw  either  saturated  or  superheated  steam  from  the 
boiler  the  cross-pieces  from  the  two  drums  of  each  boiler  are  connected  to  the  nozzle 
of  the  superheater,  by  means  of  two  angle  globe  valves  and  a  T  fitting,  as  will  be  seen 
in  the  cross-section  (Fig.  3)  of  the  plant.  As  the  pipes  lead  to  one  common  header 
and  as  the  pressure  from  one  boiler  may  easily  vary,  a  non-return  angle  valve  is  directly 
mounted  on  the  above-mentioned  tee.  From  here  a  4-inch  pipe  leads  to  the  header, 
which  is  7  inches  in  diameter.  It  would  have  been  an  easy  matter  to  have  brought 
the  pipes  from  the  header  through  the  division  wall  directly  to  the  throttles  of  the  tur- 
bines nearest  the  boiler  room,  while  in  carrying  over  to  the  other  turbines  in  this  manner 
difficulty  would  have  been  experienced  in  supporting  and  draining  the  pipes,  and  it 
would  certainly  not  have  improved  the  appearance  of  the  plant.  The  author,  there- 
fore, decided  to  bring  two  y-inch  steam  down-takes  below  the  main  operating-room 
floor,  connecting  them  here,  by  means  of  a  short  header,  in  order  to  form  a  complete 
ring.  From  this  lower  section,  as  will  be  seen  in  the  pipe  drawing  (Fig.  4),  as  well 
as  in  the  cross-section  (Fig.  3),  5-inch  pipes  run  below  the  generating-room  floor,  rising 
through  it  to  the  turbines.  A  similar  arrangement  has  been  made  for  the  exciter  units. 
The  auxiliary  machinery,  such  as  the  circulating  water  pumps,  house  pumps  and 
hot  well  pumps,  draw  their  steam  from  the  main  steam  pipe  leading  to  its  turbine. 
These  pumps  operate  under  the  same  steam  conditions  as  the  turbines,  while  the  boiler 
feed  pumps  and  the  two  small  house  pumps  are  operated  also  with  steam  of  the  same 
character,  except  that  this  steam  will  contain  a  small  amount  of  water  which  has  been 
collected  from  the  entire  pipe  system,  the  steam  for  these  pumps  being  drawn  from 
the  bottom  of  the  lowest  main  header  and  the  piping  therefore  acting  at  the  same  time 
as  a  drip  system.  There  are  no  further  traps  or  similar  features  for  draining  the 
remainder  of  the  system.  The  reason  for  this  is  that,  first,  the  steam  does  not  contain 
much  water,  which  would  not  interfere  with  the  operation  of  pumps  of  this  character, 
and,  second,  one  does  away  with  the  trap  system.  However,  the  supply  pipes  to  the 
pumps  must  be  provided  with  a  bleeder.  It  will  be  seen  in  the  accompanying  piping 
sketch  (Fig.  4)  that  the  upper  header  does  not  have  any  drip  pipe  at  all  and  the  small 
amount  of  condensation  will  run  down  into  the  lower  header,  where  all  tees  and  outside 
ends  of  valves  are  connected  by  a  f-inch  globe  valve  and  an  additional  check  valve  to  a 
short  i  £- inch  header  from  where  the  pipe  leads  to  the  above-mentioned  pumps. 

In  order  to  secure  a  proper  operation  and  so  that  any  section  of  the  pipe  may  be 
easily  cut  off  in  case  of  emergency,  non-return  valves  must  be  placed  near  the  boiler. 
The  4-inch  pipes  leading  from  the  boilers  to  the  header  may  be  cut  off  at  the  header 
by  gate  valves,  while  in  the  header  itself,  at  the  junction  of  boiler  No.  4  and  boiler 
No.  5,  are  inserted  two  y-inch  gate  valves.  One  valve  would  have  been  sufficient  were 
it  not  for  the  condensation  in  the  pipe,  as  the  latter  dead  section  of  pipe  is  45  feet  long 
and  under  ordinary  operating  conditions  does  not  carry  any  steam.  On  each  end  of 
the  steam  down-takes  valves  are  also  placed.  Besides  this  there  are  valves  inserted  at 
the  branches  leading  to  the  turbine  and  exciter  engines  in  order  to  cut  out  any  section 
of  the  pipe  in  case  of  emergency.  The  supply  pipes  to  the  turbines  have  additional 
gate  valves  close  to  the  units,  controlled  by  stands  on  the  operating-room  floor. 


3io 


STEAM-ELECTRIC   POWER   PLANTS. 


O 

U 


The  upper  as  well  as  the  lower 
header  pipes  are  well  anchored  on 
the  crane  and  building  columns, 
and  have  been  indicated  on  the 
plan  (Fig.  2),  as  well  as  in  the  pipe 
drawing  (Fig.  4).  This  has  been 
done,  first,  on  account  of  vibration, 
and,  second,  on  account  of  expan- 
sion. As  the  anchors  are  located  in 
the  middle  of  the  piping,  the  expan- 
sion has  to  extend  toward  both 
ends.  The  expansion  of  one  side 
(60  feet)  will  be  approximately  2 
inches  and  will  be  easily  taken  up 
by  the  4-inch  pipes  leading  from 
the  boilers  to  the  header,  while  the 
expansion  of  each  half  of  the  lower 
header,  each  of  which  has  a  length 
of  about  35  feet  1.2  inches,  is  taken 
up  by  the  steam  down-takes,  which 
are  some  23  feet  long.  It  will 
therefore  be  seen  that  no  expansion 
loops  are  necessary.  The  lower 
steam  header,  as  well  as  the  pipes 
leading  to  the  turbines,  is  carried 
from  the  floor  beams  above,  while 
the  upper  steam  header  is  easily 
suspended  from  the  steel  structure 
carrying  the  smoke  flue.  A 
platform  will  be  erected  directly 
beneath  the  latter  header  in  order 
to  give  easy  access  to  the  various 
valves.  This  platform  will  be 
carried  by  the  division  wall  at  one 
end  and  the  beams,  from  which 
the  boilers  are  suspended,  at  the 
other  end. 

Returning  to  the  size  of  steam 
pipes,  the  following  data  were  em- 
ployed in  the  calculations,  as  the 
manufacturers  guarantee  a  steam 
consumption  not  to  exceed  17 
pounds  per  K.W.  hour,  normal  load 


SMALL  POWER  PLANTS.  311 

for  rated  capacity,  and  as  approximately  10  per  cent  of  the  total  steam  consumption 
is  used  for  auxiliaries,  etc.,  the  20  pounds  assumed  in  the  beginning  of  the  article 
is  a  safe  assumption.  As  the  volume  of  dry  saturated  steam  at  175  pounds 
pressure  is  2.4  cubic  feet  per  pound,  the  total  volume  of  steam  per  turbine  per  hour 
would  be  275  X  17  X  2.4=  11,220  cubic  feet,  giving  a  velocity,  in  a  5 -inch  pipe,  of 
7,000  feet  per  minute.  Under  ordinary  operating  conditions  dry  saturated  steam 
is  not  used,  but  steam  superheated  about  150°  Fahr.,  which  increases  the  volume 
approximately  30  per  cent,  thus  giving  a  lineal  velocity  in  the  same  size  pipe  of 
9,100  feet  per  minute. 

Even  though  there  is  considerable  difficulty  at  times  in  securing  fittings  for  5 -inch 
piping  (the  greater  bulk  of  pipe  being  steel),  it  would  be  poor  practice  to  use  one  size 
larger  (6  inches),  as  the  velocity  would  be  only  6,500  feet  for  superheated  steam,  while 
the  velocity  in  a  4- inch  pipe  would  be  too  great  for  American  practice,  although  fre- 
quently used  on  the  Continent,  where  higher  degrees  of  superheat  are  common  prac- 
tice. For  the  same  reasons,  and  taking  well  into  consideration  the  steam  consump- 
tion of  the  auxiliaries,  4  inches  v/as  chosen  as  the  size  of  pipe  from  the  boilers  to  the 
header. 

As  four  4-inch  pipes  are  approximately  equivalent  in  carrying  capacity  to  one  7-inch 
pipe,  a  7-inch  pipe  is  therefore  chosen  for  the  header  or  ring  system. 

The  pipes  will  be  covered  with  a  thin  layer  of  asbestos  cement  upon  which  is  laid 
85  per  cent  asbestos-magnesia  sectional  covering,  held  together  with  galvanized  iron 
wire.  Over  this  an  8-ounce  canvas  covering  is  securely  sewed  and  finally  painted 
with  fireproof  paint. 

Turbines  and  Generators. — The  turbines  will  be  of  the  horizontal  type,  connected 
direct  to  the  generators  and  both  mounted  on  a  common  bedplate.  They  are  arranged, 
as  will  be  seen  in  the  plan  (Fig.  2),  side  by  side,  with  steam  ends  toward  the  middle 
of  the  room.  The  steam  connections  are  5-inch;  each  turbine  is  provided  with  a  screen 
and  throttling  valve.  After  the  steam  has  passed  through  the  turbine  it  exhausts  into 
the  condenser  through  a  24-inch  outlet. 

On  account  of  the  small  weight  of  the  turbo-generator  and  as  niuch  space  is  re- 
quired in  the  basement  for  condensers  and  their  auxiliary  machinery,  these  turbines 
are  carried  in  pairs  on  1 8-inch  beams,  which  in  turn  are  supported  on  two  concrete 
walls,  thus  giving  ample  space  between  and  around  the  condensers  and  securing  a 
good  pipe  arrangement. 

Pressure  oil  to  the  bearings  of  the  turbines  is  supplied  by  a  small  pump  operated 
from  the  main  shaft  of  the  turbine  and  mounted  on  the  main  bedplate.  After  the  oil 
has  passed  through  the  bearings,  it  is  returned  to  a  cooling  and  filtering  system  and 
used  over  again.  The  turbo-generator  has  a  normal  capacity  of  750  K.W.  and  has  an 
overload  capacity  of  50  per  cent;  it  is  of  the  revolving- field,  alternating-current  type, 
and  at  1,800  revolutions  per  minute  has  7,200  alternations  per  minute  (four  poles), 
thus  giving  sixty  cycles  per  second,  suitable  for  lighting,  power  and  railway  service  - 
for  which  purpose  this  plant  has  been  designed.  The  voltage  is  2,300.  Due  to  the 


312  STEAM-ELECTRIC   POWER  PLANTS. 

high  velocity  of  these  turbines,  a  "closed"  type  of  generator  is  employed  on  account 
of  the  otherwise  very  objectionable  noise.  This  necessitates  a  ventilating  system 
which  is  secured  by  bringing  a  fresh-air  duct  in  under  the  main  operating-room  floor 
to  a  point  directly  below  the  generator  and  discharging  up  through  the  bedplate. 
Air  is  drawn  from  the  area  at  the  side  of  the  building,  the  duct  being  turned  downward 
and  protected  with  a  netting  so  as  to  prevent  the  entrance  of  any  foreign  substances. 

Condenser  Plant.  —  The  arrangement  of  the  condenser  plant  depends  upon  the 
arrangement  of  the  turbines,  as  the  former  is  placed  directly  below  the  latter.  Each 
condenser  is  supported  on  two  I  beams,  in  turn  supported  by  the  small  concrete  piers 
and  the  turbine  foundations.  The  exhaust  of  the  turbine  is  so  arranged  as  to  dis- 
charge into  the  condenser  or  to  the  atmosphere.  For  this  purpose  an  atmospheric 
relief  valve  is  placed  in  the  exhaust  pipe  as  near  to  the  turbine  exhaust  outlet  as  pos- 
sible. A  gate  valve  is  placed  between  the  free  exhaust  and  the  condenser,  so  that  in 
case  of  repairs  to  the  latter  or  its  auxiliaries  the  turbine  may  be  operated  and  exhaust 
direct  to  the  atmosphere.  Particular  pains  must  be  taken  to  avoid  any  leakage  on 
pipes  under  vacuum,  as  this  will  materially  affect  the  latter.  A  corrugated  copper  expan- 
sion joint  is  therefore  placed  between  the  turbine  and  condenser,  as  will  be  seen  in 
the  cross-section  (Fig.  3),  to  take  up  the  expansion,  which  amounts  to  about  £  inch. 
The  exhaust  inlet  to  the  condenser  is  24  inches  in  diameter,  while  the  free  exhaust  pipe 
from  each  turbine  is  14  inches.  The  latter  size  has  been  chosen  to  obtain  a  steam 
velocity  of  5,000  feet  per  minute.  All  exhaust  piping  up  to  the  atmospheric  relief 
valve  is  of  cast  iron;  the  flanges,  after  being  carefully  bolted  together,  are  painted  with 
shellac  or  asphaltum,  while  the  rest  of  the  exhaust  piping,  with  the  exception  of  a  few 
fittings,  are  made  of  spiral  riveted  pipe.  As  will  be  seen  in  the  plan  (Fig.  2),  the  two 
14-inch  pipes  of  the  two  turbines  are  connected  to  one  pipe  20  inches  in  diameter, 
leading  into  a  20-inch  riser  terminating  a  few  feet  above  the  roof  in  an  exhaust  head. 
This  arrangement  allows  two  turbines  to  discharge  at  the  same  time  to  the  atmosphere, 
while,  under  unfavorable  conditions,  all  three  turbines  may  do  the  same. 

It  is  common  practice  to  allow  4  square  feet  cooling  surface  per  K.W.  of  turbine 
capacity,  thus  giving  3,000  feet  for  the  surface  condensers.  This  apparently  large 
surface  is  chosen,  as  at  times  muddy  or  comparatively  warm  water  is  supplied.  Under 
the  above  conditions  and  in  order  to  obtain  from  28  to  29  inches  vacuum  (barometric 
reading  30  inches),  the  liable  figure  of  70  pounds  of  water  to  condense  one  pound  of 
steam  will  be  assumed,  and  figuring  the  velocity  in  the  centrifugal  pump  at  450  feet 
per  minute,  a  lo-inch  pump  will  be  required.  As  there  will  be,  when  the  plant  is 
completed,  four  condenser  outfits,  and  as  the  velocity  in  the  main  circulating  water 
intake  must  be  about  300  feet  per  minute,  a  20-inch  pipe  will  be  required.  In  order 
to  have  more  uniformity  in  the  size  of  pipes,  the  circulating  water  discharge  pipe  will 
be  the  same  size.  Both  pipes,  after  supplying  the  first  two  condenser  units,  are 
reduced  to  16  inches.  It  will  be  noticed  in  the  accompanying  condenser  plan  (Fig.  5) 
that  two  small  house  pumps  also  draw  their  water  from  this  pipe  line.  The  duty  of 
these  pumps,  as  has  already  been  touched  upon,  is  to  make  up  the  water  lost  bv  leak- 


SMALL  POWER  PLANTS.  3*3 

age  at  the  boiler,  consumption  of  the  auxiliary  machinery,  etc.  These  pumps  are 
6X4X6  inches  and  have  3-inch  suction  and  2^-inch  discharge  pipes.  The  circu- 
lating pumps,  having  a  lo-inch  suction  and  discharge,  are  operated  by  a  single-cylinder 
horizontal  engine  (ten  inches  by  ten  inches),  and  as  the  velocity  of  the  circulating  water 
to  the  condenser  must  be  reduced,  the  pipe  leading  to  the  latter  is  12  inches  in  diameter. 
The  steam  supply  pipe  to  this  engine  is  2\  inches  and  the  exhaust  3  inches. 

The  exhaust  steam  enters  the  condenser  at  the  top,  and  as  the  condenser  is  of  the 
counter- current  type,  the  cooling  water  enters  at  the  bottom  and  is  discharged  at  the 
top,  where  a  1 2-inch  connection  is  made  to  the  main  discharge  pipe,  located  below 
the  intake  pipe  in  the  trench,  and  emptying  into  the  river.  After  the  pumps  have  been 
started  a  siphon  is  formed  and  the  pumps  are  required  to  overcome  friction  only. 
Both  intake  and  discharge  pipes  are  made  of  cast  iron  and  outside  of  the  power  house 
are  embedded  in  the  earth.  The  intake  pipe  must  be  provided  with  a  screen  and  a 
foot  valve.  The  circulating  water  pumps  will  be  primed  by  means  of  the  air  or  dry 
vacuum  pumps. 

These  latter  pumps  are  located  outside  of  the  turbine  foundations,  as  will  be  seen 
in  the  condenser  plan  (Fig.  5).  The  air  pumps  are  connected  to  the  condenser  by 
means  of  a  4-inch  pipe  and  discharge  through  a  3^-inch  pipe  into  the  main  atmospheric 
exhaust  pipe.  A  dry  vacuum  pump  6  X  14  X  10  inches  will  be  required,  the  steam 
connection  being  \\  inches  and  the  exhaust  \\  inches. 

On  the  bottom  of  the  condenser  is  a  hot  well,  where  the  condensed  steam  is  col- 
lected. From  here  the  water  is  drawn  away  through  a  3- inch  suction  pipe  by  means 
of  a  duplex  pump  (5  X  4^  X  5  inches)  and  discharged  through  a  2-inch  pipe  into  the 
make-up  tank.  These  pumps  start  automatically  by  means  of  a  regulator  in  the  hot 
well. 

Exciters  and  Air  Compressor.  —  To  secure  a  continuous  operation  of  the  plant 
two  exciter  units  are  necessary,  one  of  which  is  always  kept  in  reserve.  As  the  ulti- 
mate total  capacity  of  the  plant  is  3,000  K.W.,  one  per  cent,  or  30  K.W.,  will  be  the 
required  capacity  of  each  exciter,  this  taking  into  consideration  the  fact  that  the 
latter  cannot  be  overloaded  to  the  same  extent  as  the  main  units.  As  practically 
all  the  auxiliary  machinery  is  steam  driven,  the  exciters  are  operated  by  8  X  8- inch 
horizontal  engines,  the  steam  connection  being  2\  inches  and  the  exhaust  3  inches. 

For  the  purpose  of  blowing  out  the  generators  and  switchboard  apparatus,  an  air 
compressor  is  installed  at  one  side  in  the  switching  room.  This  is  driven  by  means 
of  a  chain  from  a  5  horse-power  motor  mounted  on  the  frame  of  the  compressor. 

Switchboard  and  Wiring  System.  —  As  already  stated,  the  switchboard  is  located 
in  the  middle  of  the  generating  room  on  the  side  wall.  The  generator  feeders  run 
under  the  floor  direct  to  the  oil  switches,  which  are  suspended  from  the  generating- 
room  floor,  from  where  they  lead  through  one  main  slot  to  the  rear  of  the  switchboard. 
The  switchboard  itself  is  made  of  marbleized  slate  mounted  on  a  steel  frame.  There 
are  four  generator  panels,  each  24  inches  wide,  two  exciter  panels,  each  16  inches  wide, 


3  14  STEAM-ELECTRIC   POWER   PLANTS. 

and  eight  feeder  panels  for  lighting  and  power,  also  each  16  inches  in  width,  and  one 
panel  for  the  sectionalizing  switches,  this  latter  being  32  inches  wide.  This  gives  a 
total  length  of  switchboard  of  about  25  feet. 

In  order  to  secure  a  flexible  system  and  at  the  same  time  insure  continuity  of  ser- 
vice and  proper  protection  for  the  entire  equipment,  the  following  apparatus  is  mounted 
on  the  various  panels.  Three  of  the  generating  panels,  the  fourth  being  left  blank  for 
a  future  unit,  each  contain  three  ammeters  for  reading  the  current  in  each  phase,  one 
wattmeter,  one  field  ammeter,  and  one  power-factor  indicator;  these  six  meters  being 
arranged  in  two  vertical  rows  on  the  upper  part  of  the  panel.  A  recording  wattmeter 
is  mounted  for  convenience  on  the  back  of  the  board.  Below  the  above-mentioned 
meters  on  the  front  of  the  board  are  symmetrically  arranged  one  field  switch,  one  poten- 
tial receptacle  and  plug,  one  synchronizing  receptacle  and  plug,  one  three-pole,  double- 
throw  oil  switch  operated  by  hand,  and  one  rheostat  wheel.  The  generator  panels. are 
mounted  at  one  end  of  the  board  and  on  the  outside  panel  is  placed  a  swinging  bracket 
containing  one  wattmeter,  one  synchroscope  and  two  synchronizing  lamps.  Adjoining 
the  generator  panels  are  the  two  exciter  panels,  each  containing  a  voltmeter,  ammeter, 
rheostat  wheel  and  a  two-pole,  single-throw  knife  switch,  the  equalizing  switches  being 
mounted  directly  at  the  machines. 

Upon  each  panel  for  the  outgoing  feeders  is  mounted  a  three-pole,  single-throw 
oil  switch  in  order  to  draw  current  from  either  of  the  two  sets  of  buses,  and  an  ammeter 
and  voltmeter,  a  wattmeter  being  unnecessary,  as  the  power  may  be  measured  at  the 
sub-station. 

A  special  lighting  panel  will  be  installed  at  the  side  of  the  office  in  the  switching 
room,  as  shown  in  Fig.  2.  This  panel  will  be  32  inches  wide,  with  the  follow- 
ing mounted  on  the  front:  one  double-pole  knife  switch  for  each  lighting  circuit  and 
one  double-pole,  double-throw  knife  switch  so  that  the  lighting  buses  may  be  thrown 
on  to  the  exciter  buses  or  on  to  the  secondary  of  a  special  lighting  transformer.  Near 
this  transformer  is  mounted  its  oil  switch.  There  is  also  a  small  three-phase  trans- 
former for  supplying  power  to  the  coal  conveyor  and  air-compressor  motors  with  the 
main  oil  switch  mounted  at  the  transformer  and  local  knife  switches  mounted  at  each 
motor. 

The  accompanying  diagram  (Fig.  6)  shows  the  main  features  of  the  wiring  dia- 
gram, small  details,  such  as  the  location  of  meters,  etc.,  being  omitted.  It  will  be 
seen  that  the  bus-bars  are  cut  up  by  means  of  sectionalizing  switches  at  four  different 
places,  one  being  between  the  outside  generators  and  two  being  between  generators 
No.  2  and  No.  3.  This  latter  precaution  has  been  taken  in  order  that  interruption  of 
the  lighting  and  motor  circuits  may  be  reduced  to  a  minimum.  It  will  be  seen  from 
the  diagram  that  the  entire  system  is  laid  out  as  symmetrically  as  possible,  and  suffi- 
cient switches  have  been  placed  so  as  to  make  the  system  as  flexible  as  possible,  and 
in  order  to  meet  any  emergency  which  may  arise  in  the  plant  itself  or  in  the  outgoing 
feeders. 

The  double  bus-bar  system  has  been  adopted  for  the  same  reason  as  the  ring  system 
in  the  steam  piping.  Both  the  wiring  and  piping  systems  are  the  main  arteries  in 


SMALL  POWER  PLANTS. 


315 


316  STEAM-ELECTRIC   POWER    PLANTS. 

their  respective  departments,  upon  which  depends  largely  the  effective  and  continuous 
operation  of  the  plant.  Current  may  be  thrown  into  either  of  the  two  buses  or  on 
both  at  the  same  time,  and  the  outgoing  feeders  may  draw  from  one  or  both  sets.  One 
bus-bar  system  may  serve  exclusively  for  light  and  the  other  for  power,  the  outgoing 
feeders  leading  underground  to  the  various  sub-stations  where  the  current  is  trans- 
formed to  voltages  suitable  for  either  light  or  power. 

Conclusion.  —  To  give  an  exact  figure  of  the  cost  of  this  plant  is  impossible,  as  it 
depends  so  largely  upon  the  location.  As  this  plant  has  been  designed  with  the  best 
possible  equipment,  using  all  first-class  material  and  with  the  point  in  view  of  reducing 
the  working  force  to  a  minimum,  assuming  that  the  site  is  convenient  for  securing  labor 
and  shipping  facilities,  the  price  of  the  plant,  with  the  complete  ultimate  equipment 
(3,000  K.W.),  would  approximate  $390,000,  or  $130  per  K.W.  normal  rating.  This 
figure  is  the  result  of  a  comparison  of  the  actual  costs  of  a  number  of  similar  plants 
which  have  come  either  directly  or  indirectly  under  the  author's  charge.  Increased  size 
and  capacity  of  a  plant  may  reduce  the  first  cost  to  about  $100  per  K.W.,  depending, 
of  course,  as  stated,  upon  the  size  of  the  plant.  An  alternative  for  reducing  the  cost 
of  the  plant,  which  unfortunately  is  too  frequently  adopted,  is  to  simplify  the  general 
layout.  Such  plants  are  built  for  the  purpose  of  putting  them  in  operation  as  soon 
as  possible,  securing  a  large  number  of  customers  and  selling  the  plant  with  a  large 
profit,  regardless  of  operating  economies.  For  following  this  scheme  the  author  would 
suggest  the  following  simplifications,  and  by  adopting  these  the  plant  may  still  be  run 
satisfactorily,  but  the  number  of  employees  and  operating  expenses  will  be  increased, 
while  the  first  cost  will  be  decreased  some  $50,000  or  $60,000,  making  about  $100  per 
K.W.  Do  away  with  boiler-room  basement,  suspended  coal  bunkers  and  suspended 
ash  hopper,  coal  and  ash  handling  conveyor  system,  mechanical  stokers,  and  also  the 
track  scale  for  weighing  the  incoming  coal.  The  coal  cars  may  be  brought  on  a  trestle 
higher  than  shown  in  the  cross-section,  so  that  the  coal  may  drop  from  the  car  and 
slide  through  an  opening  to  the  boiler-room  floor  or  be  shoveled  on  to  it.  The  ashes 
will  be  carted  away  from  the  main  operating-room  floor.  With  this  arrangement  the 
height  of  the  boiler  room  will  be  decreased  20  feet.  At  the  same  time  the  generating- 
room  basement  and  area- way  at  the  side  of  the  building  may  be  omitted,  in  which  case 
the  turbines  would  be  installed  on  frameworks  built  up  so  as  to  leave  space  for  the 
condensers,  etc.,  underneath,  and  small  pits  dug  so  as  to  accommodate  the  hot  well 
pumps. 

The  pipes,  such  as  mains,  steam,'  exhaust,  blow-off,  etc.,  will  be  placed  in  trenches. 
The  piping  system  may  be  simplified  by  omitting  some  of  the  valves,  and  also  the 
provision  for  drawing  either  superheated  or  saturated  steam.  In  fact,  the  superheaters 
themselves  may  be  omitted.  Another  saving  could  be  effected  by  simplifying  the  bus- 
bar system,  using  a  single  instead  of  a  double  system.  As  the  space  in  the  base- 
ment used  for  switching  purposes,  repair,  store,  locker  rooms,  etc.,  has  been  done 
away  with,  a  two-story  compartment  will  be  required  for  this  purpose.  The  second 
story,  of  course,  will  be  installed  directly  above  the  main  switchboard,  and  over  the 


SMALL  POWER  PLANTS.  317 

entire  length  of  the  generating  room.  From  the  total  height  of  the  generating  room 
13  feet  will  be  saved. 

Instead  of  the  generating-room  floor  being  tiled,  it  may  receive  a  granolithic  cement 
finish.  Also  the  tiled  wainscoting  around  the  room  may  be  omitted. 

Of  course,  a  case  might  arise  where  the  installation  of  condensers  and  their  auxil- 
iaries would  be  unadvisable,  depending  upon  the  character  of  the  water  supply.  Before 
laying  out  the  plant  a  close  study  of  this  feature  should  be  made. 

A  still  further  decrease  in  first  cost  could  be  obtained  by  doing  away  with  the  steel 
columns  and  having  only  the  roof  trusses  of  steel,  the  wall  being  of  brick  instead  of 
reinforced  concrete,  the  crane  runway  resting  on  brick  pilasters. 

If  the  plant  were  to  be  built  on  the  Continent,  where  the  operating  conditions  are 
considered  of  greater  importance,  and  where  still  better  results  are  desired  than  those 
obtainable  with  the  original  equipment,  the  following  design  would  have  been  adopted : 

No  stokers  would  have  been  installed,  as  labor  is  easily  obtainable  so  skilled  as  to 
produce  one  horse-power-hour  for  one  and  a  quarter  pounds  of  coal  at  12,000  British 
thermal  units  per  pound.  The  turbines  are  sold  with  the  guarantee  that  the  steam 
consumption  will  not  exceed  nine  and  a  half  to  ten  pounds  per  indicated  horse-power- 
hour  when  using  a  high  degree  of  superheat  at  175  to  200  pounds  pressure  and  a  vacuum 
of  not  less  than  27  inches,  and  everyday  practice  proves  that  these  guarantees  are  strictly 
lived  up  to.  Superheaters  will  be  installed  capable  of  furnishing  steam  at  a  total 
temperature  of  650°  to  700°  Fahr.,  which  would  not  cause  any  extra  deterioration 
in  the  turbine.  All  auxiliary  machinery  will  be  motor  driven,  and  a  small  storage 
battery  will  be  installed  for  supplying  light  for  the  station  and  exciter  current  in 
case  of  emergency.  As,  however,  warm  water  is  required  for  boiler  feed,  economizers 
will  be  installed  in  the  basement,  where  also  the  smoke  flue  will  be  arranged. 
Smoke  flue  and  chimney  will  both  be  built  of  brick. 

Owing  to  the  higher  temperature  of  the  steam  a  greater  velocity  will  be  secured, 
and  the  size  of  pipes  will  be  decreased.  The  wiring  system  will  be  a  more  com- 
plicated one. 

Assuming  that  the  total  water  consumption  of  this  plant,  including  auxiliaries, 
leakage,  etc.,  is  17  pounds  per  K.W.-hour  (a  very  unfavorable  figure  under  Continental 
conditions)  and  the  water  consumption  for  the  above-designed  plant  of  20  pounds  per 
K.W.-hour,  there  will  be  a  saving  of  3  pounds  effected.  On  account  of  the  fact  that 
the  plant  is  for  both  lighting  and  railroad  purposes,  and  will,  therefore,  have  a  widely 
fluctuating  load,  we  will  assume  that  the  total  daily  output  of  the  3,ooo-K.W.  station 
is  only  30,000  K.W. -hours.  Assuming  further  that  one  pound  of  coal  evaporates 
eight  pounds  of  water,  and  that  the  coal  cost  $2.50  per  ton,  a  saving  of  $4,180  will  be 
effected  per  year.  This  is  a  net  saving  of  fifteen  per  cent  of  the  total  coal  consumption. 


CHAPTER   IX. 
TESTING   POWER   PLANTS. 

General  Considerations.  —  All  plants,  even  though  they  be  of  small  capacity, 
should  undergo  a  rigid  test  in  order  to  prove  the  manufacturer's  guarantees.  This 
guarantee  test  should  be  made  as  soon  as  possible  after  the  plant  is  completed, 
as  it  is  upon  this  test  as  a  rule  that  the  final  payments  depend.  The  test  should  be 
conducted  or  watched  by  the  designer  of  the  plant,  so  that  he  may  see  and  rectify  any 
weak  point  that  may  appear  in  the  design,  besides  acquiring  valuable  experience  for 
future  plants.  If  a  designer  desires  to  advance  himself,  he  should  watch  the  opera- 
tion of  the  plant. 

All  tests  should  be  made  public  in  the  technical  press,  so  as  to  give  a  comparison 
with  similar  plants;  it  is  of  importance  also  to  publish  an  unsatisfactory  test,  so  that 
the  same  mistake  will  not  be  duplicated,  besides  bringing  about  a  discussion  among 
able  engineers  whose  ideas  may  rectify  the  error.  It  may  seem  that  by  thus  adver- 
tising the  failure  of  any  piece  of  apparatus,  the  manufacturer  will  be  injured.  This 
supposition  is  erroneous,  as  the  manufacturer  will  thus  be  forced  to  improve  his 
machine. 

Preparation  for  Boiler  Tests.  —  The  boiler  should  be  tested  as  to  its  economy  and 
capacity.  Before  starting  the  test,  the  boiler  and  its  auxiliary  apparatus  should  be 
placed  in  first-class  working  condition;  all  soot,  dirt  and  ashes  should  be  removed 
from  the  boiler  tubes  and  chambers,  the  tubes  cleaned  of  any  deposits  of  scale,  and 
the  grates  thoroughly  cleaned  of  clinkers,  ashes,  etc.  Tests  for  air  leaks  in  the  boiler 
setting  should  be  made,  and  any  leaks  around  poorly  fitting  doors  made  tight.  This 
last  is  doubly  important,  if  induced  draft  is  used. 

The  coal  used  for  determining  the  performance  of  a  boiler  must  be  of  the  same 
kind  as  that  to  be  used  in  the  plant  when  running.  From  the  coal  to  be  burned  samples 
should  be  taken  for  analysis,  as  described  in  the  chapter  on  coal.  The  ashes  should 
be  properly  collected  and  weighed  when  dry.  Proper  analysis  should  also  be  made 
of  the  smoke;  this  analysis  is  usually  made  by  an  expert  chemist,  but  with  modern 
instruments  the  engineer  may  accurately  determine  its  character.  This  matter  is 
more  thoroughly  discussed  in  the  chapter  on  combustion. 

For  measuring  the  feed  water  weighing  tanks  must  be  installed.  Meters  are 
seldom  used,  except  for  checking  purposes.  Thermometers  should  be  placed  in  the 
feed  lines.  All  pressure  gauges  must  be  properly  checked  before  starting  a  test,  as 

318 


TESTING  POWER  PLANTS.  319 

i 

they  are  subject  to  great  fluctuations.  The  feed  and  blow-off  piping  should  be  ex- 
posed, so  that  if  any  leak  occurs  it  may  be  detected;  all  connections  to  other  units 
should  be  blank  flanged. 

The  test  should  be  run  a  sufficient  length  of  time  to  minimize  any  slight  inaccuracy 
in  starting  and  stopping.  The  condition  of  the  boiler,  furnace,  etc.,  should  be  the 
same,  as  nearly  as  possible,  at  the  end  as  at  the  beginning  of  the  test.  The  water  level 
and  the  quantity  and  condition  of  the  fire  should  be  the  same  as  well  as  the  steam 
pressure  and  the  temperature  of  the  boiler  setting  and  flues. 

Method  of  Boiler  Tests.  —  There  are  different  methods  of  starting  and  stopping 
tests.  In  starting,  first  raise  the  steam  to  the  required  pressure,  note  the  water  level, 
then  draw  the  fire,  and  as  quickly  as  possible  start  a  new  one  with  weighed  wood  and 
coal,  accurately  noting  the  time.  When  the  test  is  completed,  note  the  water  level 
and  the  time,  remove  the  entire  fire,  which  should  be  burned  low,  and  clean  the  ash  pit. 
If  the  water  level  is  not  the  same  as  at  the  start;  correction  may  be  made  by  compu- 
tation, but  not  very  accurately  unless  the  temperature  is  the  same.  Water  in  a  boiler 
has  a  higher  coefficient  of  expansion  than  the  boiler. 

Another  method  is  to  start  by  thoroughly  cleaning  the  fire,  noting  water  level, 
pressure  and  time,  covering  the  fire  with  weighed  coal  just  before  which  the  ash  pit 
should  be  cleaned.  Before  the  end  of  the  test  the  fire  should  be  burned  low,  so  as  to 
be  in  the  same  condition  as  at  the  start,  steam  pressure,  water  level  and  time  should 
then  be  noted.  All  other  conditions,  such  as  setting  and  flue  gas  temperature,  must 
be  the  same  at  the  finish  as  at  the  start.  Provision  should  be  made  to  remove  the 
steam  as  fast  as  it  is  made,  so  that  the  rate  of  evaporation  will  be  constant.  Attention 
should  be  given  to  the  discipline  in  conducting  a  test,  so  that  all  orders  issued  by  the 
man  in  charge  be  promptly  and  intelligently  obeyed  by  the  operating  force. 

The  test  readings  should  be  made  at  frequent  and  uniform  intervals,  and  recorded 
on  a  chart.  All  small  details  should  be  noted  and  time  taken.  The  time  and  style 
of  fire  should  be  kept  uniform.  The  accompanying  report  of  a  test  on  a  35o-horse- 
power  Stirling  boiler  at  the  Public  Works  Company,  Bangor,  Maine,  gives  essential 
items  for  making  a  complete  boiler  test. 


RESULTS  OF  TEST. 


Date  of  test,  March  4th  P.M.,  and  5th  A.M., 
Duration  of  test,  in  hours 


Dimensions  and  proportions: 

Grate  surface,  square  feet 68.66 

Water  heating  surface,  square  feet 3>5°o 

Ratio  of  water  heating  surface  to  one  of  grate  surface 5°-97 

Average  pressures: 

Steam  pressure  in  boiler  by  gauge,  pounds 121.1 

Steam  pressure  absolute,  pounds I3v8 

Barometer  pressure  in  inches  of  mercury     . 29-99 

Barometer  pressure  in  pounds  per  square  inch 14-75 

Force  of  chimney  draft  in  inches  of  water 0.29 


320  STEAM-ELECTRIC  POWER  PLANTS. 

Average  temperatures: 

Temperature  of  air  outside,  deg.  F 30 

Temperature  of  fire  room,  deg.  F -. 58 

Temperature  of  the  steam  at  pressure,  deg.  F 350.4 

Temperature  of  escaping  gases  (Gauntlett  Pyrometer),  deg.  F 482.5 

Temperature  of  the  feed  water  (well  in  the  feed  pipe),  deg.  F 186.6 

Fuel: 

Kind  of  coal  used:  Big  Vein  Cumberland. 

Total  amount  of  coal  from  the  pile,  pounds 13,802 

Moisture  by  samples,  per  cent 15-36 

Moisture  in  total  coal,  pounds 2,120.6 

Dry  coal  fired  under  the  boiler,  pounds 11,681.4 

Total  refuse,  ashes,  cinders,  etc.,  pounds 638.0 

Percentage  of  refuse  in  dry  coal,  per  cent 5.46 

Total  combustible  used,  pounds 11,043.4 

Dry  coal  consumed  per  hour,  pounds 1,168.14 

Combustible  consumed  per  hour,  pounds 1,104.34 

Calorimeter  tests: 

Quality  of  steam,  dry  steam  being  taken  as  unity,  per  cent 99-44 

Moisture  in  steam,  per  cent 0.56 

Water: 

Total  weight  of  water  pumped  into  the  boiler  and  apparently  evaporated,  pounds     .    .    .  121,860.00 

Pounds  of  water  in  steam,  pounds 688.00 

Water  actually  evaporated,  corrected  for  quality  of  steam,  pounds         121,172.00 

Equivalent  water  evaporated  into  dry  steam  from  and  at  212  deg.  F.,  pounds 129,770.00 

Factor  of  evaporation 1.0709 

Equivalent  total  heat  derived  from  fuel,  B.T.U 125,320,000 

Equivalent  water  evaporated  into  dry  steam  from  and  at  212  deg.  F.  per  hour,  pounds      .  12,977.00 

Economic  Evaporation: 

Water  actually  evaporated  per  pound  of  dry  coal,  actual  pressure  and  temperature,  pounds,  10.37 

Equivalent  water  evaporated  per  pound  of  dry  coal  from  and  at  212  deg.  F.,  pounds  .    .  11.10 

Equivalent  water  evaporated  per  pound  of  combustible  from  and  at  212  deg.  F.,  pounds   .  n-75 

Rate  of  Combustion: 

Dry  coal  actually  burned  per  square  foot  of  grade  surface  per  hour,  pounds 17.01 

Dry  coal  actually  burned  per  square  foot  of  heating  surface  per  hour,  pounds 0.33 

Rate  of  Evaporation: 

Water  evaporated  from  and  at  212  deg.  F.  per  square  foot  of  grate  surface  per  hour,  pounds,  188.28 

Water  evaporated  from  and  at  212  deg.  F.  per  square  foot  of  heating  surface  per  hour,  3.70 

Commercial  Horse-Power: 

Actual  horse-power  by  the  A.S.M.E.  Code,  30  pounds  of  water  per  hour  evaporated  from 
a  temperature  of  100  deg.  F.  into  steam  of  70  pounds  steam  gauge  pressure  or  its 

equivalent,  34.487  pounds  per  hour  from  and  at  212  deg.  F.  per  hour,  H.P 37^-3° 

Horse-power,  builder's  rating,  H.P 350.00 

Horse-power  developed  above  builder's  rating,  per  cent 7-5 


TESTING  POWER  PLANTS.  321 

Efficiency: 

Heat  units  accounted  for  by  one  pound  of  coal  burned  (dry) 10,728.03 

Heat  units  in  one  pound  of  dry  coal,  Bomb  Calorimeter 13,558.00 

Theoretical  evaporation  per  pound  of  dry  coal,  pounds 13.  u 

Actual  evaporation  under  working  conditions  of  tests,  pounds i°-37 

Efficiency:  percentage  of  possible  evaporation  realized 79. 13 

Theoretical  loss  from  all  sources  (of  the  possible  heat  in  coal),  per  cent 20.87 

The  report  as  given  above  is  on  a  test  of  a  boiler  of  average  size;  that  of  a  larger 
size  is  as  follows:  the  boiler  was  of  yoo-horse-power  capacity  and  of  the  Parker  type. 

FEED.  —  The  feed  water  was  pumped  directly  into  the  boiler  from  the  weighing  tanks. 

COAL.  —  The  coal  used  was  apparently  well  burned,  but  analysis  shows  that  there  was  6.46  per  cent 
of  the  original  carbon  in  the  ash,  and  a  somewhat  higher  economy  would  probably  have  been  obtained  if  the 
boiler  had  been  operated  at  a  less  horse-power. 

ASH.  —  The  necessity  for  using  water  in  the  furnace  to  prevent  the  formation  of  large  clinkers  makes 
the  determination  of  the  exact  percentage  of  refuse,  by  drying  and  weighing  the  entire  amount  of  ash  at  this 
plant,  practically  impossible,  and  samples  were  taken  and  the  figures  entered  are  from  these  samples.  The 
analysis  of  the  coal  gave  17.87  per  cent  of  ash  and,  .making  proper  allowance  for  the  unburned  coal  in  the 
refuse,  gave  20.18  per  cent  as  the  amount  actually  obtained. 

CALORIFIC  VALUE  OF  FUEL.  —  Samples  of  the  coal  were  taken  during  the  test  and  check  values  of  the 
heat  per  pound  were  obtained  from  each  sample  on  a  Parr  Calorimeter.  This  value  was  also  calculated  from 
the  proximate  analysis  of  the  coal. 

ECONOMIC  RESULTS.  —  Ordinarily  in  determining  the  water  evaporated  per  pound  of  combustible,  all 
the  refuse  is  assumed  to  be  ash.  Really  the  volatile  matter  accompanying  the  unburned  carbon  is  utilized 
and  the  heat  apparently  obtained  per  pound  of  combustible  is  increased.  The  evaporation  was  reduced  to 
the  basis  of  combustible  supplied,  giving  11.85  pounds  per  pound  of  combustible  from  and  at  212  degrees. 
On  the  usual  basis  this  value  would  have  been  12.674  pounds. 

ANALYSIS  OF  DRY  GAS.  —  The  coal  was  properly  burned  and  the  amount  of  air  supplied  per  pound  of 
carbon  was  reasonable.  Analyses  were  made  once  an  hour.  Before  the  test  and  while  the  openings  into  the 
furnace  were  not  closed  by  the  accumulated  ash,  the  quantity  of  air  supplied  reached  as  high  as  26  pounds 
per  pound  of  carbon. 

STOKER.  —  The  data  relating  to  the  steam  and  water  supplied  to  the  stoker  show  that  about  .54  per 
cent  of  the  heat  available  was  utilized  in  heating  the  water  used  to  cool  the  stoker.  The  quantity  of  steam 
used  to  run  the  stoker  amounted  to  5.8  per  cent  of  the  boiler  capacity. 

HEAT  BALANCE.  —  The  use  made  of  the  heat  contained  in  one  pound  of  fuel  as  fired  is  shown  in  this 
table.  The  balance,  unaccounted  for,  is  partly  used  in  evaporating  part  of  the  water  supplied  to  the  ashes 
(1.15  pounds  per  pound  coal)  and  part  in  radiation.  An  error  of  5  per  cent  is  possible  in  this  heat  balance. 


DATA    AND    RESULTS   OF   THE   TEST   ON   A   7oo-HORSE-POWER   PARKER   BOILER   TO 

DETERMINE  THE  ECONOMY  OF  THE  BOILER  RUNNING  AT  THE  CAPACITY  THAT  COULD  BE 
OBTAINED  FROM  IT  UNDER  USUAL  WORKING  CONDITIONS. 

The  boilers  are  set  two  in  a  battery.     The  boiler  tested  is  the  end  one  of  the  group,  nearest  the  stack. 

The  boiler  has  a  furnace  at  each  end,  equipped  with  a  mechanical  stoker  and  grate,  the  two  grates  hav- 
ing a  common  fire  chamber.  The  two  side  bars  and  the  ash  plate  at  the  bottom  of  the  grate  are  water  cooled. 
The  cooling  water  after  use  is  led  to  a  feed  water  heater.  The  gases  pass  back  and  forth  along  the  tubes, 
being  guided  by  three  light  tile  baffles  and  leave  the  setting  at  the  top  of  the  boiler,  passing  directly  into  the 
main  flue. 

The  burned  coal  falls  over  the  ends  of  the  grates  into  a  common  ash  chamber  and  from  there  is  dropped 
at  intervals  into  barrows.  To  prevent  the  ash  from  forming  large  clinkers,  a  stream  of  water  is  distributed 


322  STEAM-ELECTRIC  POWER  PLANTS. 

over  the  ashes,  a  part  of  which  is  evaporated  and  the  balance  runs  off.  Unless  this  chamber  is  kept  fairly 
full  of  ashes,  the  leakage  of  air  into  the  furnace  is  considerable. 

The  tubes  are  4  inches  diameter,  20  feet  long,  and  with  the  exception  of  the  bottom  row  are  horizontal. 
The  bottom  row  is  inclined  to  make  a  space  for  the  superheater  tubes  and  to  carry  the  baffling  which  pro- 
tects the  superheater  tubes  from  direct  impingement  of  the  flames. 

There  are  two  drums,  4  feet  6  inches  diameter,  22  feet  between  heads,  each  drum  having  its  separate 
set  of  upper,  lower  and  superheating  elements.  The  drums  are  connected  below  the  water  line  at  the  front 
end. 

The  upper  elements  for  each  drum  are  seven  tubes  high  and  ten  tubes  wide.  Their  function  is  to  heat 
the  feed  water.  The  feed  water  enters  the  upper  element  at  the  back  beyond  the  check  valve  which  prevents 
the  water  backing  up  in  the  drums.  The  flow  is  forward  and  back  alternately  in  each  tube  in  the  top  row, 
then  down  to  the  next  row,  etc.,  finally  discharging  through  an  upcast  into  the  steam  space  of  the  drum. 
The  water  flows  along  the  diaphragm  into  the  "scale  pocket"  and  back  into  the  water  chamber  of  the 
drum.  When  the  feed  is  interrupted,  the  water  for  circulation  is  supplied  directly  from  the  drum  through 
the  check  valve  above  referred  to. 

The  lower  elements  receive  this  heated  water  and  convert  it  into  steam,  counter-flow  being  maintained 
by  checks  as  in  the  feed  elements.  The  five  elements  to  each  drum  are  each  two  tubes  wide  and  nine  tubes 
high.  The  water  coming  down  from  the  drum  enters  the  header  controlling  two  elements,  passes  through 
the  check  valve  and  then  down  through  the  tubes.  The  lower  end  of  each  element  is  connected  by  a  sepa- 
rate upcast  to  the  steam  chamber  of  its  drum. 

The  steam  furnished  by  both  drums  is  led  to  a  fitting,  from  which  5-inch  tubes  carry  it  down,  on  each 
side,  to  the  superheater  headers.  After  passing  through  the  superheater  tubes,  of  which  there  are  64,  ij 
inches  diameter  and  18  feet  long,  the  steam  is  collected  in  headers  and  another  pair  of  5-inch  tubes  carry  it  to 
the  stop  valve  casting.  These  5-inch  tubes  are  built  in  the  setting.  There  is  a  flooding  device  and  a  drain 
on  each  superheater  element. 

The  boiler  was  handled  by  the  regular  men  with  instructions  to  make  as  much  steam  as  possible  without 
wasting  coal  over  the  end  of  the  stokers. 

The  fuel  used  was  small  anthracite. 

The  furnace  was  fired  at  each  end  of  the  boiler,  two  (2)  box  stokers  being  used,  both  being  water  cooled 
and  steam  jets  used  for  draft. 

The  weather  was  clear  and  hot. 

All  the  appliances  used  in  making  the  test  were  standardized  and  all  readings  given  below  are  corrected 
readings. 

The  start  and  stop  of  the  test  was  by  what  is  known  as  the  Alternate  Method,  the  boiler  being  run  at 
the  rate  at  which  it  was  tested  three  hours  before  the  beginning  of  the  test. 

Date  of  trial,  July  17  and  18,  1905. 

Duration  of  trial,  noon  July  17,  1905,  to  noon  July  18,  1905,  24  hours. 


DIMENSIONS  AND  PROPORTIONS. 

Grate  surface:    2  each,  9'  5"  width,  7'  3"  length.     Total  area  136.5  sq.  ft. 

Height  of  furnace:    3'  front  end,  4'  9^"  back  end 

Water  heating  surface:    6,600  sq.  ft.  tubes,  325  sq.  ft.  bottom  of 

drums,  154  sq.  ft.  tops,  total 7>°79        scl-  ft- 

Superheating  surface      37^ 

Ratio  of  water-heating  surface  to  grate  surface 5T-^S  *°  r 


AVERAGE  PRESSURES. 

Steam  pressure  by  gauge  (145.5  before  superheater)   ......  143-3    lb.  Per  Sfl-  m- 

Force  of  draft  just  above  boiler 0.84  in.  of  water 

Force  of  draft  in  furnace 0.55  in.  of  water 

Barometer,  29.83  ins 14-7    lb-  Per  scl-  in- 


TESTING  POWER  PLANTS.  323 

AVERAGE  TEMPERATURE. 

Of  external  air 87.9     deg.  Fahr. 

Of  fire  room 90-2 

Of  steam  (before  superheater  363.5) 483-6 

Of  feed  water  entering  boiler ...  79.8 

Of  escaping  gases  from  boiler      486.8 

Increase  in  temperature  of  feed  water  due  to  stoker 6.65 


FUEL.  ^ 

Size  and  condition:  Fine  anthracite. 

Weight  of  coal  as  fired 75>927      lb. 

Percentage  of  moisture  in  coal 3-9  Per  cent 

Total  weight  of  dry  coal  supplied  boiler 72,966      Ib. 

Total  ash  and  refuse  — dry 18,589      Ib. 

Quality  of  ash  and  refuse  —  apparently  fairly  well  burned. 

Total  combustible 54>377      Ik- 
Percentage  of  ash  and  refuse  in  dry  coal 25.5  per  cent 

(6.46  per  cent  unburned  carbon,  20.18  per  cent  real  ash  from 
dry  coal  burned.) 


PROXIMATE  ANALYSIS  OF  COAL. 

Fixed  carbon 77-5°  Per  cent 

Volatile  matter 2.23        " 

Moisture 2.4 

Ash 17.87        " 


ANALYSIS  OF  ASH  AND  REFUSE. 

Carbon 25.34  per  cent 

Earthy  matter 74.66        " 


FUEL  PER  HOUR. 

Dry  coal  supplied  boiler  per  hour 3,040.2  Ib. 

Combustible  supplied  per  hour 2,426.7  " 

Dry  coal  per  sq.  ft.  of  grate  surface  per  hour 22.27  " 


CALORIFIC  VALUE  OF  FUEL. 

Calorific  value  by  Parr  Calorimeter,  per  Ib.  of  dry  coal      ....      11,811  B.T.U. 
Calorific  value  by  analysis,  per  Ib.  of  dry  coal  (proximate)    .    .    .      12,020        " 


QUALITY  OF  STEAM. 
Number  of  degrees  of  superheating 121.2  deg.  Fahr. 


324 


STEAM-ELECTRIC   POWER   PLANTS. 


WATER. 

Total  weight  of  water  fed  to  boiler 540,485  Ib. 

Factor  of  evaporation I-275I 

Equivalent  water  evaporated  into  dry  steam  from  and  at  212  deg.    689,172  Ib. 

WATER  PER  HOUR. 

Water  evaporated  per  hour 22,520        Ib. 

Equivalent  evaporation  per  hour  from  and  at  212  deg.  per  sq.  ft.  of 

water-heating  surface 4.06   " 

Equivalent  evaporation  per  hour  from  and  at  212  degrees   ...  28,716         " 

HORSE-POWER. 

Horse-power  developed      832.3  H.P. 

Builders'  rated  horse-power 700 

Percentage  of  builders'  rated  horse-power  developed 118.9  per  cent 

ECONOMIC  RESULTS. 

Water  apparently  evaporated  under  actual  conditions  per  Ib.  of 

coal  as  fired 7.118  Ib. 

Equivalent  evaporation  from  and  at  212  deg.  per  Ib.  01  coal  as  fired,  9.0767 

Equivalent  evaporation  from  and  at  212  deg.  per  Ib.  of  dry  coal 

supplied  boiler 9-4451 

Equivalent  evaporation  from  and  at  212  deg.  per  Ib.  of  com- 
bustible supplied  boiler 11-83 

EFFICIENCY. 

Efficiency  of  boiler:  heat  absorbed  by  the  boiler  per  ib.  of  coal 

divided  by  the  heat  obtained  from  i  Ib.  of  coal 82.76  per  cent 

Efficiency  of  boiler,  including  the  grate;  heat  absorbed  by  the 
boiler  per  Ib.  of  coal,  divided  by  the  heat  value  contained  in 
i  Ib.  of  coal 78.34 

ANALYSIS  OF  THE  DRY  GASES. 
( Volume .) 

Carbon  dioxide  (CO2) 7-82  per  cent 

Oxygen  (O) 7-5° 

Carbon  Monoxide  (CO) o^S 

Nitrogen  (by  difference)  (N)   . 84.55 

Air  supplied  per  pound  of  carbon 17.7    Ib. 

STOKER. 

Water  used  to  cool  stoker  per  min •    •  7-28  gals. 

Temperature  before  entering  stoker 7&-9  ^e 

Temperature  after  leaving  stoker "9-7S 

Equivalent  rise  in  temperature  of  feed  water    ....  6.65 


TESTING  POWER  PLANTS.  325 

STOKER  —  Continued.- 
Steam  to  stoker: 

Pressure 72.3  Ib.  per  sq.  in. 

Temperature 356-9  deg.  Fahr. 

Pressure  near  outlet  —  front  grate 28.5  Ib.  per  sq.  in. 

Pressure  near  outlet  —  back  grate 25.9     " 

Drop  in  supply  pipe  in  16  inches 4.8     " 

Steam  used  in  both  grates  per  hour 1,358       Ib. 

HEAT  BALANCE. 

Heat  in  i  Ib.  coal  with  3.9  per  cent  moisture  from  calorimeter  .      11,250        B.T.U. 

Loss  by  incomplete  combustion 132.2  B.T.U.  1.17  per  cent 

Waste  in  unburned  coal  in  ash 525-4        "  4-^7         " 

To  evaporate  3.9  per  cent  water 47.6        "  0.42         " 

Given  to  water  in  stoker 47.3        "  0.42         " 

Given  to  steam  used  in  stoker 25.2        "  0.22         " 

Heat  to  chimney  gas      *,$°9-1       "  11-64        " 

Heat  to  water  in  boiler 8,766.3        "  77-93         " 

Unaccounted  for 396.3        "  3.53         " 

Method  of  Testing  Prime  Movers.  —  Engine  or  turbine  tests  are  usually  made  to 
prove  the  efficiency  and  capacity  of  the  machine.  All  instruments  used  in  the  test 
should  be  the  best  of  their  respective  kinds  and  in  first-class  order.  The  steam  pipes 
leading  to  the  engines  should  be  cut  off  from  all  other  units,  while  the  water  of  con- 
densation from  the  cylinder  should  be  separately  collected  and  measured.  The 
engine  valves  and  pistons  should  be  tested  for  leakage;  to  ascertain  the  character  of 
the  steam,  calorimeters  may  be  connected  between  the  throttle  and  the  engine,  while 
thermometers  should  be  placed  at  the  steam  inlet  and  exhaust,  and  if  the  engine  be  of 
the  multiple  expansion  type  between  the  cylinders  also;  gauges  should  be  placed  to 
read  in  conjunction  with  the  thermometers.  The  thermometers  and  calorimeters 
should  extend  into  the  pipe,  so  that  not  only  the  steam  at  the  surface  of  the  pipe  wall 
is  tested,  but  also  the  steam  in  the  interior. 

The  amount  of  steam  consumed  by  the  engine  may  either  be  calculated  from  the 
indicator  diagrams  taken  from  each  individual  cylinder,  or  from  the  amount  of  water 
evaporated  in  the  boiler,  in  which  case  both  boiler  and  engine  test  have  to  be  run  in 
parallel.  In  the  latter  case  allowance  has  to  be  made  for  leakage  and  condensation 
in  the  pipe  line.  The  steam  consumption  of  a  condensing  engine  may  be  measured 
in  the  same  manner,  but  if  a  surface  condenser  is  used  more  accurate  results  will  be 
derived  by  measuring  the  water  of  condensation,  in  which  case  the  indicator  cards 
may  be  used  as  a  check.  The  water  of  condensation  must  be  carefully  collected  in  a 
tank  located  above  a  second  tank  on  a  beam  scale,  into  which  the  first  tank  is  drained, 
weighed  and  discharged.  These  tanks,  as  they  are  only  for  temporary  use,  are  usually 
ordinary  barrels.  If,  however,  the  owners  of  the  plant  desire  to  test  frequently  while 
the  plant  is  in  operation,  steel  tanks  should  be  provided  for  this  purpose.  There  are 
a  number  of  prominent  plants  that  have  this  system  installed. 

In  order  to  do  away  with  the  necessity  of  weighing  each  tank  of  water,  automatic 
weighing  tanks  may  be  employed.  This  system  has  been  installed  at  the  new  turbine 
station  of  the  Potomac  Electric  Power  Company,  Washington,  B.C. 


326 


STEAM-ELECTRIC   POWER   PLANTS. 


Test  of  an  Engine. — In  order  that  the  reader  may  become  conversant  with  the  best 
practice  in  operating  tests,  the  following  examples  are  submitted: 


Number  of  trial          .                ... 

I 

2 

-I 

4 

r 

6 

j 

j 

STEAM. 

Pressure  by  gauge  on  boiler  side  of 

engine  stop  valve,  pounds  per 

square  inch               , 

ii7.  t; 

II7.i; 

II7.i; 

1  14.1; 

117 

1  14.=; 

Temperature  of  steam  on  boiler  side 

/  j 

-*•     /   j 

/   J 

A  **t*0 

/ 

^  j 

of  engine  stop  valve,  deg.  Fahr. 

743 

738 

749 

726 

751 

732 

Temperatureof  steam  entering  high- 

pressure  cylinder,  degrees  Fahr. 

601 

59° 

569 

55° 

580 

558 

Superheat  of  steam  entering   high- 

pressure  cylinder,  degress  Fahr. 

253 

242 

221 

202 

232 

2IO 

EXHAUST  STEAM. 

Temperature   at   exit  from  engine, 

degrees  Fahr  

1  20 

117 

104 

no 

97.5 

93 

Temperature  of  water  leaving  hot 

well,  degrees  Fahr  

IO2 

IOI 

78 

70 

71 

64 

Vacuum  gauge,  inches  of  mercury   . 

26.4 

26.4 

27.0 

/ 

26.5 

27.4 

27.4 

POWER. 

Revolutions,  bv  counter    

TOO.  6 

100.7 

100.6 

100.7 

100.7 

100.7 

Piston  speed   in  low-pressure  cylin- 

der, in  feet  per  minute      .    .    . 

603.6 

604.2 

603.6 

604.2 

604.2 

604.2 

Indicated  horse-power  

481.3 

461.1 

347.5 

145.5 

333.5 

258.0 

HEAT  ACCOUNT  (from  32°  Fahr.) 

IN  B.T.U. 

Gross  heat  supply  entering  engine 

per  minute               

IOO,54O 

07,800 

71,060 

65,790 

51,230 

29,040 

Heat  equivalent  of  indicated  horse- 

7 1  r    y 

power  per  minute 

2O,4IO 

ICKSSO 

14,774 

14,140 

10,940 

6,170 

Per  cent  of  gross  heat           .... 

2O.  3 

7  '  j  j 
19.98 

Tl  /  O  « 
2O.7 

21.5 

21.4 

21.2 

DEDUCTIONS  (reckoned  from  hot 

"vfO 

7     7 

well  temperature). 

Heat  supplied  per  minute  per  in- 

dicated horse-power,  B.T.U,    . 

198.25 

2OI-7 

197.6 

192.1 

194.0 

194.0 

Work  actually  obtained  for  i  pounc 

of  steam,  foot-pounds    .    .    .    . 

217,700 

213,700 

222,8OO 

230,600 

228,000 

226,5OO 

Thermal  efficiency,  per  cent     .    .    . 

21.39 

2  I.  O2 

21.46 

22.07 

21.86 

21.86 

Heat      theoretically      required      by 

standard  engine,  Rankine  cycle 

B.T.U.  per  minute     

142.4 

142.5 

130.2 

128.0 

126.0 

128.5 

Efficiencv  ratio 

O.72 

0.71 

0.66 

0.67 

0.65 

0.66 

Pounds  of  steam  used  per  indicatec 

/ 

horse-power  per  hour    .    .    .    . 

9.098 

9.267 

8.886 

8.585 

8.682 

8.742 

Equivalent  consumption  of  saturatec 

steam,  reckoned  from  tempera 

ture  of  hot  well,  pounds   .    . 

10.63 

I0.8l 

10.38 

10.03 

10.07 

IO.I2 

The  test  given  above  as  reported  in  The  Mechanical  Engineer,  and  widely  dis- 
cussed in  various  other  engineering  papers,  is  a  very  exceptional  one  and  brings  out 


TESTING  POWER  PLANTS.  327 

the  great  advantage  obtained  by  the  use  of  superheated  steam.  It  will  be  noticed  that 
the  steam  consumption  in  the  fourth  test  is  as  low  as  8.585  pounds  per  I.H.P. 
hour  with  superheated  steam,  while  the  consumption  of  saturated  steam  under  the 
same  conditions  was  10.03  pounds. 

The  engine  tested  was  a  vertical  compound-marine  type,  provided  with  piston 
valves;  the  cylinders  are  not  jacketed.  It  was  built  by  Cole,  Marchent  &  Morley, 
of  Bradford,  for  the  Durham  Street  Weaving  Company,  Ltd.,  of  Belfast.  The  cylinder 
diameters  were  21  inches  and  36  inches,  the  stroke  36  inches,  thus  giving  a  cylinder 
ratio  of  2.94.  Steam  supplied  by  a  Lancashire  boiler  was  superheated  in  an  inde- 
pendently fired  Schmidt  superheater,  and  reheated  at  the  engine  just  before  entering 
the  valve  casing,  thus,  as  will  be  seen  by  the  table,  enabling  the  steam  to  be  superheated 
253°  Fahr.  (test  i)  when  it  enters  the  high-pressure  cylinder.  The  exhaust  of  the 
high-pressure  cylinder  was  again  superheated  before  entering  the  low-pressure  cylinder. 
The  methods  of  tests  and  of  calculations  were  in  accordance  with  the  recommendations 
of  the  Society  of  Mechanical  Engineers. 

Parsons  Turbine  Tests. — -The  foregoing  Table  I  gives  tests  of  Westinghouse- Parsons 
turbines  of  4oo-K.W.  to  i,25o-K.W.  capacity;  the  last  column  in  the  lower  row  represents 
a  test  of  a  2,6oo-K.W.  Brown-Boveri-Parsons  turbine.  From  this  table  the  steam 
consumption  of  the  turbine  may  be  read  under  various  operating  conditions.  An 
explanation  is  hardly  necessary:  The  table  is  taken  from  a  paper  read  by  Francis 
Hodgkinson  before  the  American  Society  of  Mechanical  Engineers. 

A  test  report  of  probably  greater  importance  to  the  plant  designer,  as  the  perform- 
ance of  the  machine  is  described,  is  given  below.  The  author  is  indebted  to  the  West- 
inghouse Machine  Company  for  the  use  of  this  report. 

The  object  of  the  tests  was  to  specifically  determine  the  fulfillment  of  the  builders' 
guarantee  of  the  steam  consumption  at  various  loads  and  under  various  conditions; 
and,  incidentally,  to  observe  the  general  efficiency  of  the  steam  turbine  for  its  intended 
work. 

The  equipment  ordered  by  Joseph  Benn  &  Sons  comprised  a  turbo-generating 
unit  consisting  of  a  600  nominal  horse-power  Westinghouse-Parsons  steam  turbine, 
direct  connected  to  a  40O-K.W.  Westinghouse  polyphase  generator  of  the  revolving  field 
type.  Both  turbine  and  generator  are  of  the  standard  construction  employed  by  the 
builders  for  machines  of  this  size. 

It  was  particularly  desired  to  determine  the  efficiency  of  the  turbine  independently 
of  the  generator,  consequently  separate  tests  were  made  on  the  steam  turbine  and  the 
generator.  To  insure  the  utmost  accuracy,  brake  tests  were  made  on  the  turbine. 
The  exhaust  steam  from  the  turbine  was  condensed  in  a  surface  condenser  and  the 
condensed  steam  weighed. 

Steam  Economy.  —  The  results  of  the  eleven  official  economy  tests  conducted 
upon  the  above-mentioned  4oo-K.W.  Westinghouse-Parsons  turbine  are  shown  in. 
the  accompanying  Table  II  and  in  graphical  form  in  Curve  Sheet  i. 


328 


STEAM-ELECTRIC   POWER   PLANTS. 


t^ 

co  r— 
co   «    o 

r^ 

^  9s        >, 

«*5 

VO 

>o 

VO 

CO 

so 

00 
IO 

-a 

•*3 

Os     IH      IN 

I-I 

•*• 

1C 

r^   os  oo 
M     CM     « 

\O       M                 *- 

^         Q 

f». 

Os 
IO 

CO 

O    r~- 

M       Tf 
CSI 

do 

M 

00 

•* 

00      VO 

so     i-i 
Tf 

•f 

vo 

00 

CO 

I-I 

u 

00 

t~-    co 

co    M     O 

^?  °°      >, 

CO 

CO 

SO 

10 

IO 

o 

t^ 

VO 

a 

1 

E 

a, 
45 

T) 
"~g 
H 

OS      IH         M 
H 

Tf 
VO 

r^    Os  OO 

CM       M       M 

%        o 

M 
l^ 

10 

CO 

0    vO 

M    so 
CO 

•* 
•<J- 

M 

t^ 

M       VO 

Tt      IH 
CN 

so" 

Os 
00 

CO 

1 

i 

SO 

M        t--      Tj- 

co    M      O 

1     9s          >, 

CO 

IT) 

Ov 
CO 

CO 

SO 

O 

P. 

5 

H 
« 

JRATKD 

cu 

0 

—  T3 

3  g 
fc,3 

OS      HI        O 

CM 

IT) 

H 

t^    Os  00 

M       M       CM 

io  <M         >r 

^        o 

CO 
IO 

CO 

O     ft 

M       Os 
10 

sS 

SO 

-t 

Os    CO 

VO        HI 
M 

<> 

CO 

Os 

cl 

M 

p 
<$ 

L 

1 

^ 

i 

o 

1 

b 
§ 

M 
oc 

'-I 

O\     M        CO 

M 

sO 
VO 

co    r-~ 

tO    Pl      q 
i-^-    Os  06 

M       M       0) 

>o 

Ch    «>• 

vo               C 

vO                    Q 
CO                   t-1 

CO 

d 
o 

IO 

CO 

0     •* 
M     ir> 

sO 

qs 
io 

N 
f^ 

10 

CSI 

VO 

OO 
O      co 

SO        M 

q^ 
o 

HH 

qs 

co 
Os 

8 

CO 

M 

|5 
t» 

s 

2 

"O 

u  g 

•^ 

^=3 
h 

Os      M        Tt- 

10 

00 

6 

IT) 

* 

vo    CO    CM 

M     M     o 
sd     Cs    f^ 

CSI       M       <N 

"?            >> 
r^    CN           Jr 

so             O 

CO 

sd 

Os 
CO 

0       M 
M       U-> 

O^ 

sO 
10 

SO 

o 

M           r^ 

M       VO                4- 

CO       M                      M 

SO 

sd 
Os 

CN 

M 

4 

1 

_o 

H 

H 

10    CM      re 
CO    CO    O 

f    *?           X 

SO 

IO 

Tt- 

M 

•>t 

CO 

VO 

VO 

CM 

3 

L 

< 
0 
< 

3 

H 

4 

-j 

00         M      SO 

CO 
vo 

t^    Os  00 

M       M       CM 

O->     CN               j- 

,00          Q 

sO 
i/"i 

CO 

0     t^ 
<si      rj- 
M 

Os 
M 

00 

•* 

VO      Tf 

O     i-i 

o 
•<? 

VO 

00 

M 

ts 

B 

L 

5 

CN 

vo    CN      co 

co    co    O 

0     ?            >, 

M 

t^ 

1^ 

VO 

Tf- 

t^ 

so 
O 

21 

C 

< 

c 

: 

5 
i 

si 

3 

~s 

3 

00        M       10 

co 
VO 

M 

t^     Os  00 
CM       0)       M 

Cs    <M              Jj 

«    0         Q 

M 
CO 
10 

CO 

o  >o 

M    so 
CO 

O 

M 
•+ 

l^ 

M       CO 
M       M 
VO 
VO 

Os 

00 

tH 

H*« 

O 

"o 

H 
H> 

fcl 

: 
; 
) 

•4 

5 

u 

c55 

Q 

E 

c- 

1 
g 

CJ-i 

2] 

00        HI        Tt 

t^ 

C1 

VO 

VO     M      f) 

PO    fO    O 
t-^-    CJs  00 
CM       N       Ot 

LO 

M                  ^ 

*~"  o         Jr 

.00           Q 

«3 

M 

O 
io 

CO 

0 
r^ 

O            M 

M       Os 

m 

co 
t-^. 
IO 

SO 

CO 

00 
^t 
t^    M' 

0     w 

CN 

ON 

f 

CO 

Os 

VO 

SO 

1 

u 

c 
n 

C 
[3 

5 
3 

< 

0 

PI 

vo    <N     ro 

ro    ro    O 

MM                      ^ 

t^. 

SO 

t 

O 

t,. 

I 

t- 

< 

0 

•< 
i 

^ 

SUPERHI 

cuum,  i 

±1 

»3 

00     M     r- 

CO 
10 

r^   O  oc 

MOM 

o    <o        Jr 

>£_  ox       G 

sO 
00 
* 
CO 

O      co 
M       0 
l^ 

t-~ 
t^ 
t^ 

-1- 

ro 

0)       M 
LO     M 

sO_ 
Os 

4- 

Os 

M 

"? 
9: 

a 

a 

0 

c/ 

fa 

fr 

•5 

•< 

5 

: 

H 

> 

CO 

*3 

00       M     CO 

so 
-f 

* 
rf     M       M 

Os    ro  \O 
\d     6s   ri- 

M       CS       C-) 

IO     CN                  ^ 

io  d         L-' 

^2      C 

00 

i 

CO 

O       M 

M     00 
00 

»o 
t-^. 

sO 
Os 

f^ 

sO 

OS                    M 

1^           so 

t^»     M                  M 

l^       PH                      M 

CO 

CO 
VO 

Os 

q 

H 

•i- 

j 
E 

c 

5 

•a 

*       n    OC1 

SO       fO     M 

C<0     Os 

"-/ 

M 

IO 

VO             Os 

IO                    M 

P4 

t^ 

= 

a 

t- 

h 

Q 
H 

3 

3 

sl 

ll*3 

^3 

b 

00         M         OS 

M 

vo 

M 

O      Os    l~- 

M       M       M 

>o    o        .> 

so      Os            C' 

Q 

Tt- 
1O 

•* 

CO 

O       M 
N       0 

H 

t^ 

O 

CSI 

00 

o 

CN 

IO    CO             CO 

SO         IH                      M 

CO 

\o~ 

SO 
Os 

M 

* 

d 

q 

^        ' 

CO 
.       <N 

P 

H 

H 

i 

H 

H 

jj 

"S 

<!          . 

vv        ob 

£     u     §       • 
bb'rt     fc!      • 

OJ    Li.      5< 

.     . 

"c 

CJ 

U 

'    £ 

-o 

.      o 

•    "o 

£ 
U 

c 

1- 

H 

c 

1 

Q 
< 

H 

e 

1URBINE  JMO.  00. 

•o 
j 

1 

B 
Z 

?  c  : 

£-    3 
-  J 

3   "5! 

M-  >      ij 

<A       O      *J 
1>      W       00 

•^    c    « 

<*-     o 

C     -M     CM 

S  2 

«    3    d 
Q  O  fc 

Steam  pressure  (gauge)  near 
per  square  inch  

Vacuum  in  exhaust  pipe,  in  H 
Barometer,  inches,  Hg.  .  . 
Vac.  refd.  30"  barometer,  in  H 

Temp,  of  steam  near  throttle,  d 
Superheat  at  turbine,  degrees  ] 
Per  cent  moisture  at  throttle,  j 
Quality  of  steam  to  turbine 

s 

Pu 

pi 

•o 
u 

& 

C/) 

'  £ 
t/i  "~ 

<u   ^r 
^1    a 

.£   1 
c   «5 

rt    u 

|-3 

2  £ 
,0 

<*H       *O 

0      U 

•£  5 

M    Sg 

C-      d) 

<u    C 
hJ    PH 

eu 
W 

T3 
U 
PL, 

- 

1 

V 

•a 

HW 

B 
w 

M<1 

G 

m 

U 

3 

a 

bb 

c 
1 

13 
rt 
_O 

3 

V 

a 

|M 

V 

PH 

£  £  t 

.  C"  P 
£   9  £,     • 

3     O 
0,    £     u       • 

M         «3         1            ' 

«    a*     . 

T3    P^    ^    JD 

|  K  ^  - 
^  PQ  w  ? 

B    V    h    3 

8  S,  &  3 
S   E   E   5 

«     flw     n 
U     V     G 

tf5    C/5    00 

di 
ffi 
« 

4 

H 
t 

PH   I. 

4; 

ffi    a 

^  ^ 
^  W 

«3 

u 

a 

H-  1 

U 
*->           O 

i         C- 

i  £ 

i  | 

J      c/; 

i 

TESTING  POWER  PLANTS. 


329 


ECONOMY  TESTS 
4OO  K.W.  STEAft  TURBINE  NO.  68 

INE  CO. 
FOR  JOS.  BENN  AND  SONS, 


800  WO  1090  1100  1900 


BRAKE  HORSE  POWE-B 


CURVE    SHEET    I 


A  comparison  of  the  builders'  guaranteed  steam  consumption  with  the  results 
obtained  under  the  various  operating  conditions  with  superheated  steam  and  with 
saturated  steam  is  shown  in  Table  III. 


TABLE  III. —  COMPARISON  OF  STEAM  CONSUMPTION  AT  VARIOUS  LOADS. 

SUPERHEATED  STEAM. 


STEAM  AT  150  LBS.  PRESSURE  AND  100°  FAHR.  SUPERHEAT,  VACUUM  28  INCHES. 

LB.  STEAM  PER  BRAKE  H.P.  PER  HOUR. 

Guaranteed  water  rate  in  Ib.  per  electrical  horse-power  per  hour    .    . 
Guaranteed  generator  efficiency     .    . 

Full  Load. 

J  Load. 

2  Load. 

14.8 

94-5% 
13.98 

J5-5 
•    93-5% 
14.49 

16.9 

91% 
I5-38 

Equivalent  water  rate  in  Ib.  per  brake  horse-power  per  hour      .    .    . 

Lbs.  steam  used  per  brake  horse-power  during  test  

12.48 
10.9% 

13-45 

7-2% 

14-34 
6-7% 

Percentage  better  than  guarantee  * 

SATURATED  STEAM. 


DRY  SATURATED  STEAM  AT  150  LB.  PRESSURE,  VACUUM  28  INCHES. 

LB.  STEAM  PER  BRAKE  H.P.  PER  HOUR. 

Guaranteed  water  rate  in  Ib.  per  electrical  horse-power  per  hour 
Guaranteed  generator  efficiency     

Full  Load. 

f  Load. 

i  Load. 

16.4 

94-5% 
15-5 

17.2 

93-5% 
1  6.8 

18.7 
91% 

t7 

Equivalent  water  rate  in  Ib.  per  brake  horse-power  per  hour      .    .    . 

Lbs.  steam  used  per  brake  horse-power  during  test       .            .... 

13.89 
10-3% 

15-05 
10.4% 

15.86 

7% 

Percentage  better  than  guarantee  .    . 

330 


STEAM-ELECTRIC    POWER    PLANTS. 


It  will  be  noted  that  the  actual  results  shown  by  the  tests  are  better  than  the  builders' 
guarantee  in  all  cases. 

If  it  is  desired  to  obtain  a  fuller  comparison  of  the  results  over  a  wider  range  of 
loads  it  can  be  found  on  Curve  Sheet  2;  curves  A  and  B  representing  the  actual 


CURVE    SHEET    2. 


results  obtained  with  saturated  and  superheated  steam  respectively,  and  curves  C 
and  D  representing  the  guaranteed  steam  consumption. 

Overload  Capacity.  —  The  tests  have  shown  the  turbine  capable  of  carrying  great 
overloads.  It  will  be  noted  that  the  extraordinary  overload  of  108  per  cent  was  carried 
by  the  turbine  with  excellent  economy.  This  desirable  feature  is  brought  about  by 
an  automatic  secondary  governor  valve,  with  which  the  turbine  is  fitted,  which  valve 
begins  to  operate  only  when  the  load  on  the  turbine  has  reached  about  700  horse- 
power, or  about  15  per  cent  overload.  This  feature  is  valuable  as  it  permits  the  turbine 
to  operate  at  its  best  economy  at  or  near  full  load  and  at  the  same  time  it  provides 
ample  means  for  sustaining  large  overloads. 

Speed  Regulation.  —  The  governor  of  the  turbine  is  so  constructed  that  its 
sensitiveness  may  be  altered  within  broad  limits.  This  turbine  unit  is  intended 
ultimately  to  operate  in  parallel,  and,  therefore,  required  a  speed  regulation  at 
or  near  4  per  cent. 


TESTING   POWER  PLANTS. 
A  governor  test  was  run  with  the  following  results: 


331 


TABLE   IV. 


Load. 

R.P.M. 

R  P.M.  Variation. 

Per   cent   of   Variation. 

O 

3,620 

+  124 

+  3-55 

* 

3.541 

+   45 

+  1.29 

Full 

3.496 

0 

o 

l| 

3.460 

-36 

—1.03 

Extreme  variation,  J  to  ij  load,  2.32%. 
Extreme  variation,  o  to  ij  load,  4.58%. 

Observations  during  the  regular  load  test  follow : 

TABLE   V. 


Load. 

R.P  M. 

R.P.M.  Variation. 

Per  cent  of 
Variation,  Normal. 

i 

3.559 

+  59 

+  1.69 

Full 

3.500 

o 

0 

ii 

3,475 

—25 

—0.71 

Twice  full 

3,45° 

—44 

—1.26 

Extreme  variation,  ^  to  twice  load,  2.95%. 

These  results  are  shown  in  the  speed  characteristic  curve  on  Curve  Sheet  i,  and 
are  somewhat  better  than  the  preliminary  governor  test. 

Superheat.  —  The  effect  of  superheated  steam  upon  turbine  economy  is  well 
indicated  by  the  divergence  of  the  two  water  lines  corresponding  to  the  tests  with 
saturated  and  superheated  steam.  This  divergence  is  practically  uniform.  (See 
Curve  Sheet  i.) 

Expressed  in  approximate  terms,  the  results  of  these  tests  indicate  that  the  steam 
consumption  is  reduced  10  per  cent  per  100°  Fahr.  superheat  throughout  the  range 
of  tests. 

Details  of  Tests.  —  The  method  of  conducting  the  tests  and  the  details  concerning 
the  calibration  of  instruments,  methods  of  measurement,  etc.,  are  referred  to  below, 
also  an  outline  of  electrical  tests  upon  the  generator. 

Methods  of  Testing.  --In  general,  the  method  employed  in  testing  the 
steam  turbine  conforms  to  the  A.  S.  M.  E.  standard  code,  but  departs  in  some 
particulars,  owing  to  the  somewhat  different  problems  involved  in  turbine  con- 
struction. 

Steam  was  furnished  from  a  boiler  plant  located  at  some  distance;  tests  with  dry 
saturated  steam  were  therefore  run  with  the  aid  of  a  superheater  because  of  the  large 
amount  of  condensation  taking  place  in  a  long  steam  pipe  line;  thus  dry  saturated 


332 


STEAM-ELECTRIC   POWER   PLANTS. 


steam  was  delivered  to  the  turbine.  As  this  superheater  was  fired  by  natural  gas,  the 
steam  temperatures  were  readily  maintained  constant. 

Exhaust  steam  was  condensed  in  a  surface  condenser  of  the  counter- current 
type,  equipped  with  a  two-stage  rotative  dry  air  pump  and  an  independent  hot 
well  pump  which  later  discharged  the  condensed  steam  directly  into  a  pair  of  weigh- 
ing tanks. 

The  water  absorption  brake  used  operates  upon  the  principle  of  the  Prony  brake, 
and  results  are  computed  in  the  same  manner.  Its  brake  arm  terminates  in  a  roller 
bearing  upon  a  block  supported  by  a  platform  scale.  Previous  to  the  test  the  eccentric 
weight  of  the"  brake  arm  was  determined  by  balancing  the  brake  on  knife-edges,  this 
weight  (about  48  pounds)  being  finally  deducted  from  the  observed  thrust  to  deter- 
mine the  net  torque  developed. 

Calibration  of  Instruments.  —  All  gauges,  thermometers  and  scales  used  in  the 
test  were  carefully  calibrated  to  insure  accuracy;  the  pressure  gauges  by  actual  test 
throughout  their  working  ranges  on  a  Crosby  gauge  tester,  the  thermometers  by  immer- 
sion in  steam  of  known  pressure  and  temperature,  and  the  scales  by  checking  with  a 
set  of  standard  weights. 


LOO  OF  TESTS 

400  K.W. 

STEAM  TURBINE 

FOR  JOS.  BENN  AND  SONS. 


CURVE   SHEET  3. 


Methods  of  Observation.  —  Steam  pressures  at  the  turbine  were  determined  by  a 
gauge   attached  close   to  the   turbine   throttle;   exhaust  pressures,*  by  compensated 

*  On  account  of  the  altitude  of  Pittsburg,  all  observations  by  mercury  column  were  reduced  to  a  basis  of  approximately  sea 
level  conditions  (barometer  =30")  for  purposes  of  ultimate  comparison. 


TESTING   POWER   PLANTS.  333 

mercury  column  attached  to  the  exhaust  end  of  the  turbine;  temperatures  of  steam 
delivered  to  turbine,  by  thermometer  immersed  in  oil  cup  at  turbine  throttle;  super- 
heat calculated  from  difference  between  observed  temperature  and  temperature  of 
saturated  steam  corresponding  to  the  observed  pressure;  speed,  measured  by  a 
reciprocating  speed  counter  connected  to  the  reciprocating  governor  motion  which  is 
geared  to  the  turbine  shaft;  steam  consumption  determined  by  weighing  the  water 
of  condensation  from  the  condenser  hot  well  by  the  alternate  method  at  intervals  of 
five  or  of  ten  minutes.  As  the  load  upon  the  turbine  was  maintained  practically  con- 
stant, the  amount  weighed  during  these  intervals  would  also  have  been  constant  except 
for  the  following  corrections: 

(a)  Condensed  Leakage  —  determined  immediately  before  and  after  regular  test 
by  closing  all  valves  leading  to  the  steam  space  of  the  condenser  and  placing  the 
condenser  under  the  same  vacuum  as  obtained  during  tests.  The  amount  of  circu- 
lating water  which  then  reached  the  condenser  hot  well  represented  the  actual  con- 
denser leakage,  which  averaged  about  5  pounds  during  an  hour's  test.  (/>)  Gland 
Water  used  for  sealing  the  packing  glands  at  the  two  ends  of  the  turbine  casing  was 
weighed  at  ten-minute  intervals  previous  to  its  passage  through  the  glands.  As  this 
water  is  finally  drawn  into  the  exhaust  passages  it  was  deducted  from  the  total  water 
condensed,  (c)  Height  of  Water  in  Hot  Well  —  from  the  known  dimensions  of  the 
condenser  hot  well,  the  weight  of  water  per  inch  of  depth  was  calculated.  The  differ- 
ence in  height  at  the  beginning  and  ending  of  the  test  was  noted  and  the  equivalent 
weight  allowed  for  in  the  final  weight  of  steam. 

These  three  corrections  applied  to  the  total  weight  of  water  at  the  end  of  the  test 
gave  the  net  weight  of  steam  supplied  to  the  turbine  during  each  one-hour  run;  had 
the  same  corrections  been  applied  at  ten-minute  intervals,  these  weights  would  have 
been  approximately  constant.  How  little  variation  actually  occurred  is  shown  on  the 
accompanying  log. 

Log  of  Tests.  —  On  Curve  Sheet  3  will  be  found  the  complete  observations 
made  during  the  eleven  tests  given  in  Table  II.  Only  such  quantities  have 
been  plotted  as  might  affect  the  economy  of  the  turbine  under  the  conditions  of 
the  test. 

Generator  Tests.  For  reasons  previously  stated,  the  turbo-generator  was  tested 
separately.  Its  characteristics  are  as  follows: 

Type:  Turbo,  revolving  field,  3-phase,  2-pole. 

Excitation:  separate 100  volt. 

Rated  full  load  capacity 400  K.  W. 

Full  load  current  per  terminal  (100  per  cent  power  factor) 527  amp. 

Voltage,  normal  .    . 440 

Frequency  (alternations  per  minute) 7200 

Speed  (revolutions  per  minute) 3600 

Methods  of  Testing  Generator.  —  In  general  the  same  methods  were  employed 
as  in  the  regular  testing  of  engine-type  generators  of  large  capacity. 


334  STEAM-ELECTRIC  POWER   PLANTS. 

The  measurements  included : 

(1)  Iron  loss  in  armature. 

(2)  Resistance  of  armature. 

(3)  Resistance  of  field. 

(4)  Saturation  curve. 

(5)  Insulation  tests. 

From  these  data  the  efficiency  is  calculated.  AS  the  losses  due  to  bearing  friction  and 
windage  are  small  and  are  not  easily  segregated  from  other  losses,  they  have  been 
neglected. 

Curve  Sheet  4  shows  the  results  of  tests,  together  with  the  efficiency  curves. 


X 


400  K.W.  WESTINGHOUSE  -  PARSONS  TURBO-GENERATOR 
FOR  JpS.  BENN  AND  SONS 


CURVE  SHEET  4. 


Efficiency  of  Generator.  —  Conforming  with  standard  practice,  efficiencies  were 
based  upon  iron  and  copper  losses,  comprising : 

(i)  Hysteresis  and  eddy  current  losses  in  armature  iron;  determined  by  driving 
the  generator  at  full  speed,  first  fully  excited  find  then  without  excitation.  The  differ- 
ence in  power  consumption  represents  the  total  iron  loss. 


TESTING  POWER  PLANTS. 


335 


(2)  C2R  loss  in  armature  coils;  determined  from  measured  resistance  of  winding. 

(3)  C2R  loss  in  field  coils;  determined  from  voltage  drop  in  windings;  checked  by 
separate  resistance  measurements. 


EFFICIENCY. 

GUARANTEED. 

MEASURED. 

EXCESS. 

Full  load 

94-5% 

96.6% 

2-1% 

}  load 

93-5 

95-7 

2.2 

\  load 

QI.O 

94.6 

3-6 

CHAPTER  X. 

THE  following  descriptive  articles  discuss  the  design  of  typical  power  plants.  It 
will  be  noted  that  such  points  as  could,  in  the  opinion  of  the  author,  be  bettered  are 
criticised.  Each  of  the  five  plants  have  their  own  particular  features  upon  which 
special  stress  has  been  laid :  as,  for  instance,  the  St.  Denis  plant,  Paris,  with  its  unique 
unit  system  and  labor-saving  devices;  the  Chelsea  plant,  London,  having  a  typical 
two-tier  boiler  house,  and  well-arranged  turbine  room;  the  59th  Street  plant,  New 
York,  being  the  largest  plant  at  present  in  operation  and  having  the  largest  recipro- 
cating engine  in  the  world;  and  the  Fisk  Street  plant,  Chicago,  a  plant  typical  of  the 
class  having  the  boiler  and  generating  rooms  at  90°,  a  system  which  has  since  been 
frequently  adopted.  The  Vienna  plant  represents  typical  Continental  practice,  and 
as  will  be  seen  throughout  the  discussion  is  laid  out  to  reduce  the  operating  cost  to  the 
minimum. 

ST.    DENIS   PLANT,    PARIS. 

On  account  of  its  departure  from  usual  practice,  a  notable  plant  still  under  con- 
struction is  the  St.  Denis  plant  of  the  Societe  d'Electricite'  de  Paris.  This  plant  is 
not  only  notable  for  being  the  largest  power  plant  in  Europe,  or  the  largest  Parsons 
turbine  plant  in  the  world,  but  on  account  of  the  number  of  separate  buildings,  the 
unique  arrangement  of  the  unit  system  and  the  many  novel  features  employed  through- 
out the  equipment.  One  of  the  principal  endeavors  in  designing  the  plant  was  the 
reduction  of  the  labor  to  a  minimum;  automatic  apparatus  being  employed  as  much  as 
possible.  As  will  be  seen  in  the  following  discussion,  the  number  of  employees  is 
extremely  small  for  a  plant  of  this  capacity.  Although,  as  will  be  pointed  out,  there 
are  items  to  be  criticised,  the  plant  is  on  the  whole  exceptionally  well  designed,  and 
serves  as  an  example  of  most  modern  engineering. 

This  plant,  which  is  located  directly  on  the  Seine,  has  been  built  to  supply  the 
city  of  Paris  and  its  suburbs  with  light  and  power,  to  assist  two  already  established 
companies,  and  to  supply  current  for  the  Metropolitan  Subway,  which  is  the  largest 
consumer.  Besides  the  above  services,  there  are  trolley  lines  near  the  plant  supplied 
with  580  volts  direct  current.  Owing  to  the  different  character  of  the  service  required 
by  these  consumers,  two  entirely  separate  and  distinct  systems  are  installed,  viz., 
3-phase,  25-cycle,  io,25o-volt,  and  2-phase,  42-cycle,  12,500  volt.  The  total  normal 
capacity  of  this  plant  amounts  to  60,000  K.W.,  three-quarters  of  which  is  3-phase  and 
one-quarter  2-phase. 

Layout.  —  Fig.  2  gives  the  general  arrangement  of  the  plant.  It  will  be  noticed 
that  there  are  three  separate  boiler  rooms  running  at  right  angles  to  one  turbo-gen- 

336 


ST.  DENIS  PLANT,  PARIS. 


337 


FIG.  i.     Exterior  of  St.  Denis  Plant,  Paris. 


FIG.  2.  Plan  of  St.  Denis  Plant,  Paris. 


338 


STEAM-ELECTRIC   POWER   PLANTS. 


erator  room,  while  on  the  opposite  side  of  the  generator  room  is  an  annex  containing 
the  switching  rooms.     In  the  rear  of  the  boiler  rooms  are  12  chimneys  and  three  sepa- 


FIG.  3.     Cross-Section,  St.  Denis  Plant,  Paris. 

rate  coal  and  ash  buildings.  Separate  feed-water  rooms  are  located  between  the  gen- 
erator and  boiler  rooms.  At  the  right-hand  end  of  the  boiler  plant  is  a  building  used 
for  offices,  canteen,  baths,  etc.,  while  between  the  two  boiler  rooms  farthest  apart  is  a 
large  storage  building. 


ST.  DENIS  PLANT,  PARIS. 


339 


340  STEAM-ELECTRIC   POWER   PLANTS. 

All  coal  is  brought  in  from  barges  on  the  Seine,  unloaded  by  a  locomotive  crane, 
and  conveyed  to  the  storage  buildings. 

The  generator  room  is  designed  to  accommodate  twelve  5,ooo-K.W.  turbo-genera- 
tors, with  the  condensers  and  auxiliary  machinery  located  in  the  basement  some  16.5 
feet  below;  this  building  is  656  feet  long  by  65.5  feet  wide.  The  boiler  rooms  are 
square  buildings,  each  140  feet  by  140  feet,  provided  with  basement  9.75  feet  high, 
with  an  economizer  floor  20.5  feet  above  the  boiler-room  floor.  The  boilers  are  of  the 
marine  type  and  arranged  in  4  rows  of  5  boilers  each,  with  a  heating  surface  of  4,500 
square  feet.  As  there  are  three  buildings  the  total  number  of  boilers  is  sixty. 

Between  the  economizers  and  above  the  firing  aisle  are  suspended  coal  bunkers 
with  a  capacity  of  40  tons  per  boiler.  Between  the  boiler  and  generating  rooms  are 
rooms  extending  the  full  width  of  the  boiler  room  and  19  feet  6  inches  wide,  used  for 
boiler  feed  purposes.  Here  are  installed  purifiers,  pumps,  storage  tanks,  etc.  The 
coal  and  ash  buildings  are  also  140  feet  square,  and  each  building  is  divided  into  4 
coal  bins  with  a  capacity  of  4,000  tons.  Between  each  boiler  house  and  coal  storage 
bin  are  four  chimneys,  making  a  total  of  twelve. 

It  will  be  noticed  that  the  entire  plant  is  spread  over  a  great  area,  wasting  a  great 
amount  of  land;  as,  for  instance,  the  space  between  the  boiler  rooms.  Considering, 
however,  the  space  occupied  by  the  individual  boiler  rooms  and  generator  room,  the 
layout  is  very  compact,  and  as  will  be  seen  in  the  accompanying  illustration  of  the 
generator  room,  the  turbines  are  laid  out  so  as  to  give  more  than  ample  room  around 
the  units.  The  following  figures  show  the  space  occupied  per  K.W.  of  the  boiler,  gen- 
erator and  switching  rooms;  the  coal  storage  buildings  are  not  considered,  as  it 
would  not  be  justifiable  to  consider  same. 

Boiler  room      1.12  Sq.  Ft.  per  K.W. 

Generator  room .70 

Switching  room .26 

Total 2.08        " 

Including  the  total  area  of  the  rectangle  occupied  by  the  plant,  including  the  chim- 
neys, but  not  the  coal  bins,  a  ground  space  2.89  feet  per  K.W.  is  the  result. 

The  plant  is  divided  up  into  a  unit  system.  Each  four  turbo-generator  unit  is 
supplied  by  one  boiler  plant,  with  four  chimneys  and  one  coal  storage  building.  This 
gross  unit  may  be  subdivided  so  that  one  turbo-generator,  having  its  own  condenser 
plant,  is  supplied  by  one  row  of  five  boilers  with  chimney  and  one  coal  storage  bin. 
The  first  gross  unit  has  been  in  operation  since  1906,  the  second  gross  unit  being 
finished  at  the  end  of  1907,  and  the  third  unit  will  soon  follow,  completing  the  plant. 
Should  necessity  arise  this  plant  may  be  easily  extended  on  account  of  this  particular 
arrangement  of  the  unit  system. 

Coal  and  Ash  Handling  Systems.  — The  coal  is  brought  in  barges  on  the  Seine  and 
unloaded  by  two  electrically  operated  locomotive  cranes.  The  coal  is  lifted  by  grab- 
buckets,  crushed,  automatically  weighed  and  elevated  by  bucket  conveyors  to  the 


_  LJLT5.5L 


{<«.4.<Sf.f<ZifM{(<('SS2Z£££f.iZZ:. 


p'Dooooooouuuoovooouooooouoooooooo 


3OOOOOOOOOOOOOOOCOOOOOOOOOOOOOOOO 


OOOOOOOOOOOOO  OX)  O 


O  O-OOOOOOOO  OOOOOOOOOOOOO  OOOOOOOOO 
OOOO'QOOOOOO  OOOOOOOOOOOO  OOOOOOOO^ 


OOOOOOOOOOOOOOOaOOOOOOOQOOOOOOO 

ooooooo  oooooooooooo  ooooaoooooo  o 


tgEgSgy^ifg.^ '.SmgftV*:'  r^ 


Cent 


"Hr  i 

FIG.  6.      Boiler,  Economizer,  etc.,  St.  I 


-/fev^^^V>^^^^ 

I  '        '   '^;v- ••--'•'.:•• 


B 


Denis  Plant,  Paris  (Journal  Le  Genie  Civil). 


ST.  DENIS  PLANT,  PARIS.  341 

storage  bins,  or  it  may  be  transferred  directly  to  the  bunkers  in  the  boiler  room.  The 
coal  from  the  storage  bins  may  be  automatically  reclaimed,  as  will  be  seen  in  the  accom- 
panying illustration,  weighed  and  conveyed,  also  by  means  of  bucket  conveyors,  to  the 
suspended  bunkers  in  the  boiler  rooms.  The  fine  coal  falling  through  the  boiler  chain 
grates  is  reclaimed  and  conveyed  back  to  the  suspended  bunkers.  The  ashes  are  con- 
veyed in  a  similar  way  and  elevated  into  the  ash  pit  in  the  front  of  the  coal  storage 
buildings,  whence  they  may  be  dumped  into  carts  and  drawn  away  or  conveyed  to  the 
barges  at  the  river. 

There  are  installed  two  locomotive  cranes  and  two  main  conveyors  to  the  various 
buildings,  two  conveyors  in  each  coal  storage  building  and  two  conveyors  for  each 
boiler  house  (one  for  each  firing  aisle).  All  these  conveyor  mechanisms  are  electrically 
operated. 

The  locomotive  cranes  and  the  main  conveyors  are  each  designed  to  handle  from 
40  to  50  tons  of  coal  per  hour.  Each  storage  building  has  a  capacity  of  16,000  tons 
and  is  divided  into  4  equal  bins.  The  suspended  coal  bunkers  in  the  boiler  room  are 
made  up  of  rolled  steel,  each  having  a  capacity  of  80  tons  per  two  opposite  boilers. 
It  must  be  noted  that  these  bunkers  are  not  continuous,  but  each  two  boilers  have  their 
own  individual  bunker,  14.5  feet  long.  This  design  is  complicated  and  increases  the 
first  cost,  while  the  coal  storage  capacity  is  materially  cut  down.  These  disadvantages 
outweigh  the  one  redeeming  feature,  increased  light  and  ventilation.  From  each 
bunker  two  conical  down-takes  lead  to  each  boiler.  There  is  a  separate  down-take 
at  the  end  of  the  boiler  room  leading  vertically  to  the  center  of  the  firing  aisle,  from 
which  coal  may  be  taken  to  any  of  the  boilers  in  case  of  emergency. 

Boiler  Room.  —  As  has  already  been  pointed  out,  each  boiler  room  contains 
20  boilers  in  four  rows,  thus  giving  two  firing  aisles.  The  boilers  are  of  the  Babcock  & 
Wilcox  marine  type,  separately  set.  The  heating  surface  of  4,500  square  feet  per 
boiler  is  made  up  of  one  5 2 -inch  drum,  15.75  feet  long,  and  33  sections  of  14  tubes  each, 
10  feet  long  and  3^  inches  diameter.  The  floor  space  occupied  by  each  boiler  is  267 
square  feet.  Each  boiler  is  provided  with  two  chain  grate  stokers,  the  combined  grate 
surface  being  70  square  feet.  One  row  of  10  grates  is  operated  from  one  lo-horse- 
power  motor. 

Directly  above  each  boiler  is  installed  a  superheater  of  640  square  feet  capable  of 
furnishing  680°  Fahr.  superheat  at  175  pounds,  as  has  been  proven  by  test.  As, 
however,  the  turbines  are  designed  for  a  total  temperature  of  570°  or  200°  Fahr.  super- 
heat, provision  is  made  to  regulate  the  temperature.  Some  20.5  feet  above  the  boiler- 
room  floor  is  located  the  economizer  floor. 

There  is  installed  for  each  boiler  one  economizer,  having  a  heating  surface  of  1,720 
square  feet.  The  scrapers  of  one  row  of  economizers  (5)  are  operated  by  a  i5-horse- 
power  motor.  The  total  height  of  the  boiler  house  from  basement  to  roof  peak  is  65 
feet.  It  will  be  seen  that  the  entire  structure  has  been  kept  extremely  low,  and  in  fact  it 
is  impossible  to  walk  on  the  top  of  the  boilers  to  make  repairs,  etc.,  while,  on  the  other 
hand,  much  space  is  wasted  in  the  other  direction,  the  firing  aisles  being  27  feet  wide. 


342 


STEAM-ELECTRIC   POWER   PLANTS. 


Superheaters  and  economizers  may  be  easily  by-passed,  the  smoke  passing  directly 
to  the  chimneys.  The  latter  are  165  feet  above  the  fire  grates  and  have  a  diameter 
at  the  top  of  10  feet.  Each  row  of  five  boilers  has  one  chimney. 

Feed- Water  Plant.  —  A  separate  feed-water  plant  for  each  gross  unit  is  located 
between  the  generator  rooms  and  the  boiler  room.  It  contains  3  triplex  double-acting 
pumps,  operated  by  80  horse-power  motors,  and  i  centrifugal  pump  operated  by  a 
loo-horse-power  motor.  Each  pump  has  an  hourly  capacity  of  1,980  gallons  (U.S.) 


FIG.  7.        Interior  of  Boiler  Room,  St.  Denis  Plant,  Paris  (Electrical  Pevieui). 

or  1,650  gallons  (British).  Besides  the  water-storage  tanks,  each  plant  contains  two 
water-purifying  systems,  each  having  an  hourly  capacity  of  185  gallons  (U.S.)  or  145 
gallons  (British).  The  extremely  small  capacity  of  these  purifiers  is  accounted  for 
by  the  fact  that  the  water  of  condensation  is  returned  to  the  boilers  and  this  purifier 
plant  is  used  only  for  the  make-up  water,  for  losses,  etc.,  which  is  drawn  from  the 
river  Seine. 

From  this  feed-water  plant  the  supply  for  the  entire  twenty  boilers  is  controlled  by 
one  attendant.  Although  these  boilers  are  equipped  with  water  columns,  magnetic 
mechanical  indicators  are  installed,  which  indicate  the  water  levels  in  the  various 
boilers.  It  will  te  seen  that  by  this  system  uniformity  in  the  water  supply,  as  well 
as  a  material  saving  in  labor,  is  effected. 


ST.  DENIS  PLANT,   PARIS. 


343 


Turbo-Generators.  —  The  turbo-generators  are  of  the  Brown-Boveri-Parsons 
type,  each  having  a  normal  capacity  of  5,000  K.W.,  with  a  maximum  overload  capacity 
of  20  per  cent.  The  entire  generating  room  has  been  designed  for  twelve  such  units; 
the  author,  however,  understands  that  in  the  near  future  larger  turbines  will  be  installed. 
These  turbines  are  designed  for  a  steam  pressure  of  175  pounds  and  superheat  of 
575°  Fahr.,and  are  under  a  vacuum  of  not  less  than  27  inches;  the  guaranteed  steam  con- 
sumption per  K.W.-hour  is  14.7  pounds.  They  are  direct-connected  to  the  generators, 
but  are  not  mounted  on  a  common  bedplate.  The  generator  and  the  bearings  on 


FIG.  8.     Interior  of  Generating  Room,  St.  Denis  Plant,  Paris. 

each  side  are  bolted  to  one  bedplate,  while  the  bearing  at  the  high-pressure  side  of  the 
turbine  has  a  separate  bedplate,  the  space  between  the  plates  being  18.5  feet.  The 
turbine  casing  is  suspended  between  these  two  bearings,  and  provision  is  made  to  allow 
the  outside  bearing  to  slide  on  the  bedplate  in  order  to  take  up  the  expansion  and 
contraction.  The  turbines  rest  on  boxgirders,  the  deepest  of  which  is  26  inches,  and 
in  order  to  reduce  the  resonance  of  these  girders  the  space  between  same  is  filled  with 
concrete. 

As  previously  stated  the  generators  are  5OO-K.W.  capacity  and  run  at  750  R.P.M. 
3-phase,  25  cycles,  10,250  volt  and  2-phase,  42  cycles,  12,500  volt.  The  over-all 
dimensions  of  the  turbo-generator  unit  are  47  feet  9  inches  long  and  15  feet  7  inches 


344 


STEAM-ELECTRIC   POWER   PLANTS. 


wide,  while  the  highest  point  of  the  turbo-generator  is  1 1  feet  6  inches  above  the  floor 
level.  It  may  be  of  interest  to  mention  the  rapidity  with  which  these  units  were  in- 
stalled. One  of  these  5,ooo-K.W.  units  arrived  at  the  power  house  on  a  Saturday  even- 
ing and  eight  working  days  later  was  in  operation. 


FIG.  9.     5000-K.W.  Brown-Bo veri-Parsons  Turbo-Generator,  St.  Denis  Plant,  Paris. 


Condenser  Plant.  —  The  entire  condenser  plant  is  located  in  the  basement,  as 
will  be  seen  in  the  accompanying  illustration.  The  four  turbines  in  one  gross  unit  are 
arranged  in  two  rows  with  the  steam  ends  facing  each  other,  thus  allowing  the  four 
condensers  to  be  symmetrically  arranged  together  in  the  basement,  with  an  opening  in 
the  main  operating-room  floor,  giving  an  unobstructed  view  of  the  entire  condenser 
plant.  The  circulating  water  is  taken  from  the  Seine  and  two  separate  intake  and 
discharge  tunnels  are  provided,  thus  giving  a  very  symmetrical  arrangement  but 
expensive  system.  On  both  sides  of  the  intake  tunnels  are  provided  suction  wells 
some  60  feet  deep  and  6  feet  in  diameter.  These  wells  are  interconnected  by  a  conduit. 
As  will  be  seen  in  the  cross-section,  the  flow  from  the  intake  tunnels  to  the  suction 
wells  is  provided  with  sluice  gates  operated  from  the  condenser  or  basement  floor. 
The  discharge,  as  will  be  noted,  is  located  in  the  center  of  the  plant  just  below  the 
basement. 


345 


346 


STEAM-ELECTRIC   POWER   PLANTS. 


Each  turbine  is  provided  with  its  own  condenser  plant,  the  condenser  itself  being 
located  directly  below  the  exhaust  outlet,  the  connecting  flanges  being  water-sealed 
to  preserve  a  high  vacuum.  On  account  of  the  above-mentioned  provision  made  for 
the  expansion  of  the  turbine,  one  end  of  the  condenser  is  placed  on  rolls.  Owing 
to  the  high  lift  of  the  cooling  water,  the  circulating  pumps,  which  are  of  the  double 
suction  centrifugal  type,  had  to  be  placed  in  the  sub-basement.  The  vertical  motors 
operating  these  pumps  are  located  on  the  main  condenser  floor  and  are  of  i5o-horse- 


FIG.  ii.     Side  Elevation  of  a  Turbine  Unit,  St.  Denis  Plant,  Paris. 

power  capacity  each.     The  air  pumps  are  of  the  three-cylinder,  single-acting  type 
and  are  operated  by  5o-horse-power  horizontal  motors. 

Auxiliary  Electrical  Equipment.  —  As  the  entire  auxiliary  apparatus  of  the  plant  is 
electrically  driven,  the  electrical  equipment  is  a  most  complete  ere. 

The  exciter  plant  consists  of  one  300-K.W.  2 20- volt  turbo-generator  provided  with 
its  own  condenser  equipment,  consisting  of  surface  condenser,  a  i6.5-horse-powcr 
circulating  pump  and  a  p-horse-power  air  pump. 

There  are  two  375-K.W.  motor  generator  sets  for  supplying  direct  current  for  the 
various  motors,  exciting  the  alternators,  operating  the  condensers  and  boiler  feed 
pumps,  coal  and  ash  conveyors  and  for  lighting  purposes,  etc.  The  motors  are 
operated  on  3-phase,  10,250  volt,  25  cycles,  and  the  dynamos  generate  current  at 
220  volts.  Besides  this  there  is  also  a  uo-horse-power  booster  set  for  charging  a 
126-cell  battery  with  a  capacity  of  1,300  ampere  one-hour  discharge  rate. 

A  very  interesting  and  unique  feature  of  this  plant  is  the  "polymorphic"  group, 
a  machine  made  up  by  assembling  four  different  machines  on  a  single  shaft,  as  shown 
in  the  illustration.  This  group  is  made  up  of  two  motors  and  two  generators.  At 


ST.  DENIS  POWER  PLANT,  PARIS. 


347 


FIG.  12.     50-H.P.  Motor-Driven  Wet  Air  Pump,  St.  Denis  Plant,  Paris  (Power). 


FIG.  13.     Polymorphic  Set,  St.  Denis  Plant,  Paris  (Electrical  Revieu?). 


348 


STEAM-ELECTRIC   POWER   PLANTS. 


each  end  of  the  shaft  is  one  5 50- volt  direct-current  generator,  between  which  is  one 
3-phase,  25-cycle,  10,250- volt  alternator,  and  one  2-phase,  42-cycle,  i2,3oo-volt 
alternator,  the  latter  being  also  arranged  to  give  6,150  volts.  In  the  middle  of  the 
group  is  an  electrically  operated  mechanical  clutch  coupling,  making  it  possible  to 
use  the  group  in  two  sets  or,  if  required,  the  two  alternators,  each  having  a  capacity 
of  750  K.W.,  may  operate  together  under  a  load  of  1,500  K.W.  on  the  55o-volt  service. 
It  is  also  possible  with  this  group  to  balance  .the  load  on  the  two  alternator  systems 
by  running  either  the  25-cycle  or  the  42-cycle  machines  or  a  motor. 

Switching  Room.  —  By  studying  the  cross-section  of  the  switching  rooms  it  will  be 
noticed  that  the  various  types  of  apparatus  are  kept  in  separate  rooms.     Starting  in 


FIG.  14.     Switch  and  Controlling  Benches,  St.  Denis  Plant,  Paris. 

compartment  "D,"  which  contains  the  generator  leads,  the  current  flows  in  alpha- 
betical order  from  one  compartment  to  the  other,  the  apparatus  being  located  as  fol- 
lows: "E,"  main  generator  switches;  "F,"  the  main  bus-bars;  "G,"  rheostats;  "H," 
taking  the  entire  upper  floor,  contains  the  controlling  bench  boards  and  the  low-ten- 
sion switchboards.  No  high-tension  current  gets  into  the  upper  compartment,  but  is 
carried  across  to  compartment  "J,"  where  are  located  the  feeder  switches.  Com- 
partment "K"  contains  the  bus-bar  junction  switches,  while  "L"  contains  the  poten- 
tial regulators.  The  last  compartment,  "M,"  serves  for  the  outgoing  cables.  There 
is  also  another  small  switchboard  on  the  main  generating- room  floor  shown  in  the  cross- 
section  "C,"  and  more  clearly  illustrated  in  interior  view  of  the  generating  room. 


FIFTY-NINTH  STREET  PLANT,  NEW  YORK.  349 

This  board  is  located  directly  beneath  the  stairs  leading  to  the  main  controlling  floor, 
and  contains  the  switches  and  instruments  required  for  the  control  of  the  exciter  unit, 
motor  generator  sets,  booster,  polymorphic  group,  etc. 

All  oil  switches  are  hand  operated  through  connecting  rods,  from  the  main  control- 
ling floor.  While  the  bus-bars  are  not  placed  in  compartments,  they  are  separated  by 
means  of  horizontal  shelves  left  open  at  the  front,  and  are  supported  on  triple  petticoat 
porcelain  insulators  carried  on  cast-iron  brackets. 

Operating  Force.  —  As  already  pointed  out  in  the  beginning  of  the  discussion, 
special  attention  has  been  given  to  the  reduction  of  the  operating  force  of  the  plant, 
and  the  following  list  shows  with  what  result.  This  list  refers  to  one  gross  unit  con- 
sisting of  one  boiler  plant  of  20  boilers,  4  turbo-generators,  20,000  K.W.,  with  all  elec- 
trical and  mechanical  auxiliaries  necessary  to  make  a  complete  plant. 

i  Superintendent, 
i  Engine  tender. 

1  Helper. 

2  Electricians. 

1  Fireman. 

2  Helpers. 

i  Feed-water  tender. 

1  Helper. 

2  Ash  tenders. 

2  Conveyor  tenders. 

The  day  is  divided  into  three  shifts,  and  during  the  daytime,  when  coal  has  to  be 
unloaded,  repairs  made,  etc.,  there  is  an  additional  force  of  three,  viz.: 

i  Crane  man. 

i   Master  machinist. 

i  Machinist. 

When  the  plant  is  completed,  with  three  gross  units  (60,000  K.W.),  the  above  force 
will  not  be  proportionately  increased,  but  will  be  smaller. 

Not  including  the  output  of  auxiliary  machinery  and  figuring  the  plant  at  normal 
rated  capacity,  when  the  greatest  number  of  men  are  employed,  there  will  be  only  one 
man  for  each  1,200  K.W.,  while  in  other  shifts  there  is  one  man  for  each  1,500  K.W. 

FIFTY-NINTH  STREET  PLANT,  NEW  YORK. 

For  operating  the  Subway  System  of  New  York  City  a  power  plant  has  been  erected 
between  58th  Street,  5Qth  Street  and  nth  Avenue  and  the  Hudson  River.  This  plant 
is  one  of  the  largest  steam-electric  power  plants  in  the  United  States,  and,  although  it 
possesses  but  few  novel  features,  it  is  prominent  because  of  its  capacity. 

The  station  is  693  feet  9  inches  long  and  200  feet  10  inches  wide,  while  a  space  of 
250  feet  is  left  to  the  river  bank,  part  of  which  may  be  built  upon  at  some  future  date 


350 


STEAM-ELECTRIC   POWER   PLANTS. 


for  an  extension.  The  boiler  room  is  separated  from  the  generating  room  by  means 
of  a  division  wall ;  the  room  runs  the  entire  length  of  the  plant  and  is  83  feet  i  inch  wide, 
while  the  generating  room  is  1 1 7  feet  9  inches  wide,  including  the  23  feet  space  for 
switching  room,  and  18  feet  for  the  so-called  pipe  gallery. 

The  boiler  room  contains  a  basement  14  feet  6  inches  high,  one  boiler  floor  37  feet 
high,  one  economizer  floor  and  a  coal  bunker,  the  top  of  which  is  93  feet  above  the 
basement  floor.  The  coal  conveyors  are  5  feet  above  the  top  of  the  bunkers.  The 
peak  of  the  roof  is  122  feet  9  inches  above  the  basement  floor.  The  basement  of  the 


FIG.  r.     59th  St.  Plant,  New  York. 

engine  room,  which  is  flush  with  that  of  the  boiler  room,  is  22  feet  6  inches  high,  while 
the  pipe  gallery  is  15  feet  6  inches  above  the  generating-room  floor.  Opposite  to  the 
pipe  gallery  is  the  switching  room,  which  contains  in  the  basement  a  gallery  13  feet 
6  inches  above  the  basement  floor,  while  the  switchboard  gallery  is  29  feet  above  the 
generating-room  floor.  The  top  of  the  crane  runway  is  64  feet  7  inches  above  the 
engine-room  floor.  The  peak  of  the  roof  is  123  feet  9  inches. 

The  steel  work  used  in  this  building  is  self-supporting,  and  all  floor  beams,  etc.,  are 
carried  as  much  as  possible  upon  the  steel  work,  instead  of  on  the  building  walls.  Some 
12,300  tons  of  structural  steel  has  been  used.  The  walls  are  of  red  brick  of  extra  good 


FIFTY-NINTH   STREET  PLANT,   NEW  YORK.  351 

quality,  faced  with  gray  tile,  harmonizing  with  the  terra  cotta  so  prominently  used. 
The  style  of  the  building  is  supposedly  French  renaissance.  A  great  deal  of  granite 
has  been  used  up  to  the  water  table  and  for  framing  doors  and  windows.  The  roof 
is  constructed  of  hollow  fireproof  tiles,  covered  with  dark  green  Spanish  tile.  Con- 
sidering the  price  of  the  structure,  which  amounted  to  $1,933,000  (including 
structural  steel),  it  does  not  appear,  architecturally,  as  handsome  as  it  might.  Besides 
the  fine  ornamental  work  with  which  the  three  main  walls  are  decorated,  it  does  not 
harmonize  with  the  five  naked  prominent  stacks.  If  the  walls  had  been  designed 
without  any  terra  cotta,  of  heavy  massive  pilasters  and  prominent  windows,  the  whole 
plant  would  have  a  more  impressive  and  powerful  appearance,  designating  the  char- 
acter of  the  plant,  which  is  a  feature  that  should  not  be  lost  sight  of  in  the  design  of 
large  plants. 

The  layout  of  the  plant  is  designed  on  the  unit  system,  each  two  prime  movers 
having  their  own  two  complete  condenser  plants,  12  boilers  (6  batteries),  two  boiler- 
feed  pumps,  four  economizers  and  one  chimney.  The  ultimate  normal  capacity  for 
which  the  plant  has  been  designed  is  90,000  horse-power. 

Circulating  Water  System.  — Condenser  water  is  drawn  directly  from  the  Hudson 
River.  The  intake  and  outlet  tunnels,  the  latter  above  the  former  as  shown  in  cross- 
section,  are  run  beneath  the  sidewalk  of  58th  Street  and  along  practically  the  entire 
length  of  the  building.  The  reason  the  tunnels  were  located  on  58th  Street  was 
that  the  original  intention  was  to  locate  the  condensers  in  the  center  of  the  plant  between 
the  generator  room  and  the  boiler  room  in  the  pipe  area,  beneath  which  the  circulating 
pumps  are  located. 

The  intake  tunnel  has  an  area  of  82  square  feet,  while  the  area  of  the  outlet  is 
70  square  feet.  Both  tunnels  are  made  of  concrete  and  rest  at  the  river  end  on  piles." 
This  latter  section,  some  65  feet  long,  was  built  in  a  floating  caisson  and  sunk  19  feet 
6  inches  below  mean  high-water  mark,  resting  on  the  aforementioned  piles,  which 
had  been  cut  off  at  this  depth.  In  order  that  the  discharge  water  will  not  flow  directly 
back  into  the  intake,  the  outlet  tunnel  has  been  extended  40  feet  into  the  river  beyond 
the  intake.  This  latter  section  is  a  wooden  flume,  supported  from  the  dock.  The 
intake  is  provided  with  a  rough  and  fine  screen. 

Coal  and  Ash  Handling  Systems. — On  the  above-mentioned  dock  there  are  two 
coal-hoisting  towers.  One  of  these  towers  is  movable  and  has  a  capacity  of  200  tons 
per  hour;  it  is  provided  with  a  i^-ton  grab-bucket  and  is  operated  by  steam.  The 
other  tower  is  fixed  and  is  electrically  driven,  having  a  capacity  of  150  tons  per  hour. 
The  grab-bucket  is  of  one-ton  capacity. 

The  coal  is  crushed,  weighed  and  delivered  on  a  30-inch  motor-driven  belt  con- 
veyor to  the  foot  of  58th  Street,  thence  it  is  transferred  to  another  conveyor  located 
in  a  tunnel  at  the  side  of  the  water  intake  tunnel  leading  to  the  end  wall  of  the  power 
house.  From  here  the  coal  is  picked  up  by  another  belt  conveyor.  As  these  con- 
veyors will  not  run  at  an  angle  greater  than  23°,  it  was  necessary  to  install  four  of  them 


352 


STEAM-ELECTRIC   POWER  PLANTS. 


i-1r>  Avtnut 


bo   <u 

W  I 


w 


9  5 

o  U 


V 

H 

eft 

3 


V 

525 


O 
PH 


c/: 

4? 


o        „ 


rt     W> 

S  "I  8, 


c-  s 

I  -? 


^  e  -s  £ 

,.         B     ^    uErf 


S  <; 


|-f  HE? 

-     ' 


FIG.  3.     Cross-Section  of  the  59th  St.  Plai 


ant,  New  York  (Zeitschrift  des  Vercincs  deutscher  Ingenieure). 


-HE 

V 


FIFTY-NINTH  STREET  PLANT,  NEW  YORK. 


353 


to  bring  the  coal  to  the  top  of  the  bunkers.  After  reaching  the  top  of  the  bunkers 
the  coal  is  unloaded  on  one  of  the  two  20-inch  longitudinal  conveyors  for  distribution 
over  the  bunkers.  Due  to  the  considerable  length  of  these  latter  conveyors,  the  power 
house  being  693  feet  long,  they  had  to  be  divided  in  two.  The  total  carrying  distance 
of  these  belt  conveyors  is  1,450  feet. 

It  will  be  seen  that  this  arrangement  of  coal  conveying  is  a  very  cumbersome  one, 
belt  conveyors  being  hardly  adaptable  for  elevating  coal  some  no  feet  in  such  a  narrow 
space.  Besides  it  is  necessary  to  install  a  great  number  of  motors,  and  if  one  of  these, 


FIG.  4.     Coal  Down-Takes,  59th  St.  Plant,  New  York  (Zeitschrift  des  Vereines 

deutscher  Ingenieure) . 


or  should  one  of  the  belts,  break  down,  the  entire  system  would  be  paralyzed,  which 
is  doubly  serious,  for  the  system  is  not  in  duplicate.  Of  course,  the  coal  bunkers, 
of  which  there  are  seven,  having  a  total  capacity  of  15,000  tons,  would  run  the  plant 
for  a  considerable  length  of  time.  Another  disadvantage  of  this  system  is  the  fact  that 
should  the  building  be  extended,  a  possibility  which  might  easily  arise  in  New  York, 
due  to  its  railway  conditions,  the  entire  elevating  system  would  have  to  be  renewed. 
On  the  economizer  floor  there  are  installed  two  motor-driven  scraper  conveyor 
systems.  These  conveyors  had  also  to  be  divided  into  two  sections  because  of  their 


354  STEAM-ELECTRIC   POWER   PLANTS. 

length.  These  conveyors  have  been  installed  for  the  purpose  of  distributing  coal 
from  any  bunker  to  any  boiler.  Coals  of  different  grades  may  be  stored  in  different 
bunkers,  so  with  this  system,  where  the  load  is  light,  a  low  grade  of  coal  may  be  burned 
in  the  boilers  and  vice  versa. 

The  coal  down-takes  from  the  main  bunkers  to  the  scraper  conveyors  are  14  inches 
in  diameter,  while  from  the  receiving  hopper  of  the  conveyor  to  the  top  of  the  boiler 
the  down-take  is  also  14  inches,  dividing  at  the  top  of  the  boiler  into  two  lo-inch  pipes. 

The  boilers  are  provided  with  plate  steel  ash  hoppers,  lined  with  hollow  tile.  The 
soot  hoppers  in  the  rear  of  the  boilers  are  of  cast  iron.  Ashes  are  removed  by  a  narrow- 
gauge  railway  system  located  beneath  each  row  of  boilers.  The  ashes  are  drawn 
to  the  water  edge  by  a  storage  battery  locomotive  to  a  receiving  hopper.  From  here 
the  ashes  are  taken  by  means  of  a  belt  conveyor  on  to  barges. 

Boilers.  — The  boilers  are  arranged  in  two  rows  facing  each  other,  with  a  single 
firing  aisle,  20  feet  wide,  running  between  them.  The  building  has  to  accommodate 
72  boilers,  of  which  60  are  installed.  They  are  of  the  Babcock  &  Wilcox  type  and 
have  a  heating  surface  of  6,008  square  feet  each,  made  up  of  three  42-inch  drums 
and  14  by  21  4-inch  tubes.  The  boilers  are  designed  for  200  pounds  working  pressure. 

There  are  two  different  styles  of  grates,  42  are  of  the  Roncy  stoker  type  and  18 
hand-fired.  However,  at  present  additional  mechanical  stokers  are  being  installed. 
The  mechanical  stokers  have  a  grate  surface  of  in. 8  square  feet,  while  the  hand- 
fired  have  100  square  feet.  A  forced  draft  system  has  been  installed  for  the  hand- 
fired  grates. 

Experiments  are  being  carried  on  on  some  of  the  boilers  at  present  by  placing  a  second 
furnace  in  the  rear  of  the  present  furnace,  a  system  similar  to  the  Hornsby  horizontal 
boilers  (10,850  square  feet)  installed  in  the  Bow  Street  station,  London. 

Twelve  boilers  have  been  provided  with  superheaters  (8  having  a  heating  surface 
of  768  square  feet  each,  and  the  remainder  900  square  feet  each),  and  supply  steam 
to  the  turbines  and  one  adjoining  prime  mover.  It  was  this  prime  mover  that  was 
tested  and  reported  before  the  American  Institute  of  Electrical  Engineers  in  January, 
1906. 

Removal  of  Gases.  —  As  already  pointed  out,  the  plant  is  arranged  on  the  unit 
system.  For  each  chimney  there  are  12  boilers  arranged  in  batteries  of  two,  three 
batteries  on  each  side  of  the  firing  aisle.  For  such  a  unit  there  are  four  economizers, 
as  will  be  seen  later.  From  the  rear  of  each  boiler  two  smoke  uptakes  rise  and  join 
by  means  of  a  sand-packed  expansion  joint  to  a  horizontal  flue  located  on  the  econ- 
omizer floor.  The  economizers  may  be  by-passed,  if  necessary,  and  the  gases  dis- 
charged directly  to  another  large  rectangular  uptake,  entering  the  chimney  at  the  sides. 
The  circular  uptakes  are  lined  with  4- inch  hollow  radial  brick,  while  the  horizontal 
flues,  of  which  there  are  four  for  each  chimney,  are  lined  with  8-inch  brick.  Two 
of  these  latter  are  connected  by  one  vertical  riser  to  the  chimney. 

A  notable  feature  is  the  way  the  radial  brick  chimneys  are  carried  on  the  steel  work 
of  the  building  some  84  feet  above  the  basement  floor.  The  diameter  at  the  top  is 


FIFTY-NINTH  STREET  PLANT,   NEW  YORK.  355 

15  feet  and  is  218  feet  above  the  grates.     This  subject  is  more  thoroughly  treated  in 
the  article  on  chimneys. 

Feed- Water  Supply.  —  As  already  pointed  out,  for  each  six  boilers  there  is  installed 
one  boiler  feed  pump,  located  at  the  side  of  the  generating  room,  together  with  the 
condenser  pumps.  These  pumps  are  of  the  vertical  compound  duplex  type,  12  inches 
by  17  inches  by  15  inches,  capable  of  handling  100,000  pounds  of  water  per  hour, 
against  a  head  of  225  pounds.  As  the  feed  water  is  drawn  from  the  city  main,  large 
storage  tanks  had  to  be  installed,  so  that  in  case  of  emergency  the  entire  plant  would 
not  have  to  be  shut  down.  There  are  at  present  eight  tanks  installed  in  the  basement 
of  the  boiler  room  beneath  the  firing  aisle,  each  having  a  capacity  of  2,200  gallons. 

Eleven  closed  vertical  feed-water  heaters  are  arranged  above  the  pumps  in  the 
pipe  area,  having  a  total  heating  surface  of  5,500  square  feet.  It  may  be  stated  here 
that  these  heaters  have  already  been  removed  and  replaced  by  open  feed- water  heaters. 

The  boiler  house  was  designed  for  the  installation  of  economizers,  but  with  the 
first  equipment  only  four  were  installed,  this  number  having  recently  been  increased 
to  14,  giving  a  total  heating  surface  of  107,600  square  feet.  The  plant  is  arranged  for 
a  total  installation  of  24  economizers. 

Main  Steam  Piping.  —  One  of  the  most  noticeable  extravagances  in  this  power 
plant  is  the  main  steam  piping.  From  each  of  the  six  6oo-horse-power  boilers  a  9- inch 
pipe  leads  to  an  i8-inch  (O.D.)  header,  which  enters  the  pipe  area  where  it  joins  a 
short  vertical  manifold.  This  pipe  area  is  18  feet  wide  and  15.5  feet  above  the  floor 
of  the  main  generator  room,  and  separated  from  the  latter  by  a  partition  wall.  It  runs 
the  entire  length  of  the  generating  room,  and  contains  the  so-called  equalizing  pipe 
system,  besides  the  heaters.  The  purpose  of  this  system  is  to  assure  against  acci- 
dents and  to  equalize  the  pressure  in  all  steam  mains  throughout  the  entire  plant,  so  as 
to  facilitate  the  paralleling  of  all  units.  There  are  ten  vertical  manifolds  for  the  ten- 
unit  plant,  which  are  interconnected  by  a  system  of  three  lo-inch  pipes. 

As  the  power  house  is  693  feet  long,  it  will  be  seen  that  the  expansion  of  these 
equalizing  pipes,  which  run  the  entire  length  of  the  power  house,  is  enormous.  The 
pipes  between  consecutive  manifolds  are  therefore  shaped  in  the  form  of  a  return  "U," 
thus  giving  the  entire  equalizing  pipe  system  a  serpentine  effect. 

From  the  top  of  each  manifold  two  14-inch  sweeping  steam  down-takes  lead  to  the 
basement  of  two  separators  at  the  base  of  the  engine  foundations.  The  height  of 
these  down- takes  is  approximately  60  feet.  From  these  separators,  which  are  3  feet  in 
diameter  and  10  feet  long,  two  i4-5nch  pipes  lead  upward  some  15  feet  to  the  bottom 
of  the  engine  cylinders.  Each  engine  is  therefore  provided  with  two  throttle  valves, 
which  forces  the  attendant  in  starting  this  unit  to  go  from  one  valve  to  the  other.  Near 
the  engine,  as  well  as  at  the  boiler  outlet,  quick-closing  valves  are  provided.  A  great 
number  of  valves  have  been  installed  in  the  pipe  area,  a  large  percentage  of  which 
extends  through  the  partition  wall  to  a  gallery  overhanging  the  generating  room,  from 
where  they  may  be  operated. 


STEAM-ELECTRIC   POWER   PLANTS. 


FIFTY-NINTH  STREET   PLANT,  NEW  YORK. 


357 


Considering  the  pipes,  one  is  immediately  impressed  with  their  enormous  size. 
For  instance,  the  p-inch  pipe  at  the  boiler  should  have  been  6  inches,  while  instead  of 
two  i4-inch  pipes  for  each  prime  mover  (5,ooo-K.W.  unit),  one  would  have  been  far 
better,  not  only  on  account  of  efficiency  of  operation  but  also  first  cost.  Thus  the 
velocity  of  steam  would  have  been  in  the  neighborhood  of  6,000  feet  per  minute,  which 
is  common  for  American  practice  with  the  use  of  saturated  steam. 

Considering  the  lo-inch  equalizing  pipe  system,  the  total  length  of  which  is  1,390 
feet,  it  seems  rather  extravagant  on  account  of  the  improbability  of  a  break-down,  espe- 


FIG.  6.      5,ooo-K.W.  Alternator,  5Qth  St.  Plant,  New  York  (Street  Railway  Journal). 

daily  as  the  designer  pointed  out  that  all  piping  was  designed  50  per  cent  stronger 
than  the  so-called  "extra  heavy"  piping. 

The  total  length  of  the  main  steam  piping  for  the  present  equipment  (50,000  K.W.) 
is  6,430  feet.  This  does  not  include  the  auxiliary  piping,  which  is  of  considerable 
length  and  size.  All  fittings  are  of  special  design,  thus  still  further  increasing  the  cost. 

In  order  to  make  possible  a  comparison  of  power  plant  piping  costs,  it  is  of  interest 
to  note  that  the  entire  piping  of  the  plant  amounts  to  approximately  $450,000.  or  $9.00 
per  K.W.  normal  capacity. 

Main  Prime  Movers.  —  The  plant  has  been  laid  out  to  accommodate  twelve  7,500 
horse-power  Allis-Chalmers  combined  horizontal  vertical  cross  compound  engines  (see 
article  on  reciprocating  engines).  There  are,  however,  only  nine  installed  at  present, 
while  space  is  left  for  two  additional  units,  which  will  in  all  probability  be  turbines. 


358 


STEAM-ELECTRIC   POWER   PLANTS. 


After  the  plant  had  been  laid  out  it  was  decided  to  install  instead  of  a  tenth  engine 
unit  four  i,25o-K.W.  Parsons  turbines  (three  at  present  installed),  as  may  be  seen  in  the 
accompanying  plan.  These  turbines  occupy  the  space  between  engines  Nos.  6  and  8. 
Upon  the  shafts  of  the  main  prime  movers  are  mounted  5,ooo-K.W.,  25-cycle,  3-phase, 
1,000- volt,  revolving  field  alternators,  having  a  speed  of  75  R.P.M. 

Main  Condenser  Plant.  —  Each  prime  mover  is  provided,  as  they  are  of  the  com- 
bined system,  with  two  Alberger  barometric  tube  condensers.     The  condensing  cham- 


FIG.  7.     Low  Pressure  Side  of  Engines  and  Condensers,  59th  St.  Plant,  New  York. 

bers  are  connected  by  an  equalizing  pipe,  so  as  to  carry  a  uniform  vacuum  in  each. 
Each  set  of  condensers  has  its  own  circulating  pump  and  air  pump.  These  pumps, 
together  with  the  boiler  feed  pumps,  are  located  on  one  side  of  the  generator  room, 
beneath  the  pipe  area.  The  pumps  are  of  the  vertical  type,  as  it  was  the  intention  to 
keep  the  steam  cylinders  of  all  the  pumps  here  located  above  the  main  floor,  so  that 
the  engine  attendant  might  easily  watch  the  operation  of  the  same.  However,  with 
the  change  of  location  of  the  condensers  from  the  pipe  area  to  the  opposite  side  of  the 


FIFTY-NINTH  STREET  PLANT,   NEW  YORK. 


359 


engine  room,  difficulties  were  encountered  with  the  air  pump,  the  result  of  which  is 
that  the  entire  air  pump  is  below  the  main  operating-room  floor. 

The  circulating  pump,  is  of  the  vertical  double-acting  compound  type,  14  x  20 
X  30  x  20  inches.  The  suction  of  the  pump  is  24  inches  while  the  discharge  to  the 
condenser  is  18  inches,  which  branches  into  two  14  inches  to  each  condenser  vessel. 
All  the  pumps  are  cross  connected  so  that  one  may  be  used  on  an  adjoining  con- 
denser. The  air  pumps  are  single  acting,  the  steam  cylinder  being  8  inches  diameter, 
24  inches  stroke  and  run  at  a  speed  of  80  R.P.M.  The  tail  pipe  discharges  into  a 
reinforced  concrete  hot  well.  Should  the  engine  run  non- condensing  an  automatic 
relief  valve  discharges  the  steam  to  the  atmosphere  through  two  30- inch  riveted  steel 
plate  pipes,  connecting  to  a  40- inch  riser,  which  takes  care  of  two  engines,  increasing, 
after  passing  through  the  roof,  to  48  inches,  on  the  top  of  which  is  an  8-foot  exhaust 
head.  In  the  horizontal  lines  and  in  the  lower  end  of  the  vertical  riser,  corrugated 
copper  expansion  joints  are  installed;  in  the  upper  end  of  the  vertical  riser  there  are 
two  slip  expansion  joints. 

Turbo-Generators.  — -  For  lighting  the  subway  three  Westinghouse-Parsons  turbo- 
generators are  installed.     These  are  of  i,25o-K.W.  capacity,  3-phase,  6o-cycle,  1,100- 


FIG.  8.     General  Diagram  of  n,ooo-Volt  Circuit.  59th  St.  Plant,  New  York. 

volt.  Space  is  left  for  a  fourth  similar  unit.  Each  turbine  has  its  own  condenser 
equipment,  consisting  of  a  surface  condenser,  4,500  feet  cooling  surface,  a  horizontal 
two-stage  dry  vacuum  pump,  and  a  horizontal  duplex  hot  well  pump.  The  three  con- 
densers are  supplied  with  circulating  water  by  one  i6-inch  centrifugal  pump,  direct- 
connected  toagxiSXQ  inch  compound  engine.  The  entire  condenser  equipment 
is  located  directly  beneath  the  turbines. 

Electrical  Equipment.  —  There  are  two  Westinghouse  vertical  cross  compound 
(17  X  27  X  24  inches)  engines,  direct  connected  to  250-K.W.  25o-volt  generators,  run- 
ning at  150  R.P.M.  There  are  also  three  250-K.W.  motor  generator  sets.  The  steam- 
driven  exciters  are  located,  as  will  be  seen  in  the  plan,  at  the  end  of  the  turbines  (prac- 


360 


STEAM-ELECTRIC   POWER   PLANTS. 


tically  in  the  middle  of  the  plant),  while  the  motor  generators  are  not,  as  shown  in  the 
plan,  between  the  steam  driven  exciters,  but  distributed  between  the  main  generator 
units,  although  kept  near  the  middle  of  the  plant. 

A  i2o-cell  storage  battery  is  installed  to  float  on  the  exciter  buses,  having  a  one- 
hour  capacity  of  3,000  amperes. 

Switching  Room.  —  The  room  set  apart  for  switching  purpose  is  23  feet  wide 
and  runs  the  entire  length  of  the  generating  room,  and  consists  of  three  floors.  How- 
ever, the  switching  apparatus  does  not  occupy  the  entire  space  of  the  third  floor,  as 
there  are  rooms  left  for  offices,  repair  shops,  etc.  The  generator  leads  run  beneath 
the  main  engine-room  floor,  in  clay  ducts,  to  the  gallery  in  the  basement,  where  the 
two  sets  of  main  bus-bars  are  located,  the  latter  running  practically  the  entire  length 


FIG.  9.     Diagram  of  the  Main  Controlling  Board,  59th  St.  Plant,  New  York. 

of  the  building.  The  generator  switches  and  the  feeder  switches,  which  are  all  of  the 
motor  operated  oil  type,  are  arranged  on  the  engine-room  floor  level.  Some  29  feet 
above  the  engine-room  floor  is  the  controlling-room  gallery,  containing  the  various 
switchboards;  the  controlling  benches  are  located  practically  opposite  the  center  of 
the  engine  room.  There  is  no  high-tension  current  whatever  in  this  gallery,  as  the 
1 1, ooo- volt  oil  switches  are  operated  by  motors  supplied  from  a  storage  battery  of 
55  cells.  Complete  dummy  bus-bar  system  is  laid  out  on  top  of  the  bench,  in  order  to 
simplify  the  operation,  especially  for  new  attendants.  The  complete  switchboard 
equipment  is  as  follows:  One  board  for  generator  and  feeder  instruments,  one  operating 
bench  for  generator  and  feeder  oil  switches,  one  exciter  current  switchboard,  one  for 
auxiliary  power,  one  operating  bench  for  60- cycle  (subway  lighting  system),  one  board 
for  60- cycle  system  instruments  and  one  board  for  power  plant  lighting. 

The  wiring  diagram  is  shown  in  Chapter  VIII,  where  also  some  other  illustrations 
of  the  electrical  equipment  are  given.  The  accompanying  cut  shows  the  bus-bar 
system  of  this  plant  and  is  self-explanatory.  The  oil  switches  used  are  of  the  General 
Electric  Company's  motor  operated  type.  Each  generator  has  one  main  and  two 
selector  oil  switches.  There  is  one  group  bus  for  each  eight  feeders  and  two  selector 
switches  for  each  group  bus. 


CHELSEA  PLANT,  LONDON.  361 

Cranes.  —  The  generator-room  cranes  are  located  68  feet  7  inches  above  the  main 
operating  floor.  There  are  installed  two  cranes,  one  having  a  capacity  of  50  tons  and 
the  other  of  25  tons.  The  former  has  two  hoists,  one  5<D-ton  and  one  lo-ton,  so  that  the 
smaller  material  may  be  more  rapidly  handled.  The  span  of  these  cranes  is  72  feet. 

Oiling  System.  —  The  plant  is  equipped  with  a  gravity  ring  oiling  system,  consist- 
ing of  duplicate  4-inch  mains.  The  oil  from  the  various  prime  movers  returns  by 
gravity  to  filters  located  at  one  end  of  the  power  house,  where  it  is  purified  and  pumped 
to  two  elevated  tanks  by  means  of  two  steam  actuated  piston  pumps.  The  supply 
tanks  are  located  at  a  height  sufficient  to  create  a  head  of  25  pounds.  The  return 
piping  is  of  wrought  iron,  the  supply  piping  of  brass. 

There  are  two  filtering  tanks  having  a  capacity  of  13,000  gallons,  and  containing 
1,200  canvas  bags,  3  inches  in  diameter  and  10  inches  long.  These  bags  are  so  arranged 
that  they  may  be  readily  removed  and  replaced  by  clean  ones. 


CHELSEA  PLANT,  LONDON. 

The  above-named  station  furnishes  the  power  for  the  London  underground  railway 
and  is  the  most  prominent  station  in  Great  Britain.  The  total  normal  capacity  amounts 
to  about  42,700  K.W. 

The  plant  is  located  on  Chelsea  Creek  at  its  junction  with  the  Thames  River. 
Fig.  i  shows  the  location  of  the  plant  and  its  various  auxiliary  requirements.  The 
most  prominent  feature,  besides  the  main  building,  is  the  large  basin  to  facilitate  the 
handling  of  coal,  and  a  separate  building  containing  an  oil-cooling  plant. 

Substructure.  —  Great  difficulty  was  encountered  in  the  foundations,  as  same  had 
to  be  carried  down  some  thirty-five  feet,  and  a  retaining  wall  had  to  be  built  along  the 
entire  water  front  of  the  site.  Some  98,000  cubic  yards  of  earth  were  excavated  over 
the  entire  lot,  and  40,000  cubic  yards  of  concrete  were  used  in  the  substructure.  These 
figures  include  the  excavation  and  concrete  floor  for  the  barge  basin,  which  is  220  feet 
long  by  80  feet  wide. 

Circulating  Water  Supply.  —  In  order  to  supply  the  circulating  water,  a  pipe  system 
has  been  installed  from  the  Thames  to  the  power  house,  as  may  be  seen  in  Fig.  i. 
The  valve  chamber  is  located  close  to  the  Thames  on  the  side  of  the  barge  basin.  From 
the  middle  of  the  Thames  to  this  valve  chamber  two  5-foot  6-inch  cast-iron  pipes  have 
been  embedded  in  the  river  bottom.  From  this  point  on  the  pipes  are  of  wrought  iron, 
running  under  the  barge  basin  and  oil-cooling  house  into  the  engine  room.  The  pipes 
reduce  at  each  suction  connection  in  the  engine  room  and  are  at  the  final  unit  2  feet 
6  inches  in  diameter.  One  of  the  pipes  is  used  as  an  outlet  and  the  other  as  an  intake; 
they  are  cross  connected,  so  that  their  duties  may  be  reversed,  that  is,  the  outlet  may 
be  used  as  the  intake,  and  vice  versa.  By  this  means  the  pipes  become  self-cleaning, 


362 


STEAM-ELECTRIC   POWER   PLANTS. 


as  any  accumulation  of  dirt  in  the  intake  will  be  washed  out  when  the  pipe  is  used  as 
an  outlet. 

Coal  Handling  System. — The  barge  basin  is  constructed  of  granite  blocks  of  about 
five  tons  each,  while  the  floor  is  of  1 2-inch  concrete  reinforced  with  expanded  metal, 
and  is  large  enough  to  accommodate  six  barges  at  one  time.  A  pneumatically  operated 
gate  is  provided  at  the  entrance  to  the  basin,  so  as  to  keep  the  water  level  constant  with 
the  high-water  mark  of  the  river.  A  by-pass  gate  48  inches  in  diameter  is  also  pro- 
vided to  regulate  the  water  level  in  the  basin. 

Two  electrically  operated  gantry  cranes  unload  the  coal  by  means  of  i^-ton  grab 
shells  upon  a  i5-horse-power  motor  driven  3o-inch  belt  conveyor,  which  carries  the 
coal  to  a  point  near  the  building,  emptying  into  two  bucket  conveyors,  which  elevate 


LOTS  ROAD 


FIG.  i.     General  Plan,  Chelsea  Plant,  London  (The  Tramway  and  Railway  World). 

the  coal  above  the  coal  bunkers  in  the  boiler  room  (some  145  feet  high),  from  which 
it  is  distributed  by  means  of  two  24-inch  belt  conveyors  to  the  various  bunkers.  Each 
bucket  conveyor  is  operated  by  a  3<>horse-power  motor,  while  the  24-inch  belts 
are  driven  by  20-horse-power  motors.  Arrangement  has  been  made  for  taking  the 
coal  from  the  western  end  of  the  building,  from  the  siding  of  the  West  London  Exten- 
sion Railway.  This  railroad  is  on  the  opposite  side  of  the  Chelsea  Creek  and  it  will 
be  necessary  to  install  a  bucket  conveyor,  overspanning  the  creek  and  running  to  the 
top  of  the  boiler  room,  where  the  coal  may  be  dumped  on  the  two  horizontal  belt  con- 
veyors above  mentioned. 

Superstructure.  — The  power  house  is  453  feet  long,  175  feet  wide  and  140  feet 
from  the  basement  floor  to  the  peak  of  the  boiler-house  roof.  It  is  divided  by  a  par- 
tition wall,  which  separates  the  boiler  and  engine  room,  the  former  being  100  feet  wide 
and  the  latter  75  feet  wide.  This  also  includes  the  space  required  for  the  switching 
department. 


CHELSEA  PLANT,  LONDON 


The  boiler  room  is  de- 
signed with  a  basement  19 
feet  high,  and  has  two  tiers 
of  boilers;  the  lower  tier  is 
33  feet  high.  Above  the 
second  tier  is  a  coal  bunker, 
capable  of  holding  15,000 
tons.  Accommodaticn  is 
made  for  80  boilers,  each 
having  a  heating  surface 
of  5,212  square  feet.  At 
the  present,  however,  there 
are  but  64  of  these  boilers 
installed. 

The  generating  room, 
which  has  a  basement  of  the 
same  height  as  that  under 
the  boiler  room,  is  50  feet 
high  between  operating- 
room  floor  and  bottom  of 
the  roof  truss.  The  total 
height  from  basement  to 
the  peak  of  the  roof  is  100 
feet.  A  space  of  14  feet 
width  is  set  apart  for  the 
entire  length  of  the  general- 
ing  room  for  the  switching 
room.  The  ten  5,5oo-K.W. 
turbine  units  are  arranged 
in  two  rows  and  staggered; 
the  condensers  are  placed 
in  the  basement  between 
the  two  rows.  By  studying 
the  cross-sections  of  the 
plant  one  will  notice  that, 
with  the  exception  of  the 
generating  room,  the  design 
has  been  followed  of  the 
74th  Street  station  in  New 
York,  for  instance,  the 
arrangement  of  the  boilers 
in  two  tiers,  with  the  econ- 
omizers in  the  rear  of  the 
boilers,  the  coal  bunkers, 


STEAM-ELECTRIC   POWER   PLANTS. 


the  arrangement  of  the  chimneys,  etc.     Besides  this  the  main  steam-pipe  system  is 
laid  out  on  the  same  principle  as  that  at   the  74th  Street  plant,  which   is,  although 


80  SO  100 


FIG.  3.     Cross-Section  of  Chelsea  Plant,  London. 


flexible,  a  very  expensive  system  and  could  easily  be  simplified.  There  are,  however, 
some  exceptions,  as,  for  instance,  chain-grate  stokers,  instead  of  incline  stokers,  and 
the  installation  of  a  superheater. 

The  steel  work  for  the  superstructure  and  the  walls  are  self-supporting.     The 


CHELSEA  PLANT,  LONDON,  365 

following  table,  as  given  in  The  Tramway  and  Railway  World,  gives  the  material 
used  in  the  building  : 

Fletton  bricks  (9"  X  4 \"  X  3") 6,000,000 

Terra  Cotta  in  strong  courses,  arches,  cornices,  etc 17,000  cu.  ft. 

Specially  made  arch  brick,  all  of  different  pattern 85,000 

Red  pressed  facing  bricks 85,000 

Portland  cement      600  tons. 

Hydraulic  lime 260      " 

Glass  in  windows 50,000  sq.  ft. 

Paint 25  tons. 

Steel  work  in  framing  and  structure 6,000 

Sundry  steel  and  ironwork  not  included  in  main  structure    .    .  2,000      " 

Boilers.  — The  boilers  are  of  the  Babcock  &  Wilcox  type  and  are  arranged  in  two 
rows  in  each  tier,  two  boilers  in  a  battery,  each  having  a  heating  surface  of  5,212  square 
feet.  They  are  capable  of  evaporating  17,000  to  18,000  pounds  of  water  per  hour. 
The  tubes  employed  are  arranged  in  twenty  sections,  twelve  high.  The  boilers  are 
designed  for  175  pounds  working  pressure. 

The  mechanical  stokers  are  of  the  motor  driven  chain-grate  type,  two  stokers  for 
each  boiler,  and  have  a  total  area  of  83  square  feet.  The  coal  is  fed  to  the  stokers 
through  chutes  from  the  coal  bunkers,  while  the  ashes  drop  into  a  suspended  steel 
hopper  and  are  carried  away  by  means  of  a  storage-battery  locomotive  on  a  narrow- 
gauge  railway  to  an  ash  pocket  outside  of  the  building,  or  may  dump  into  barge,  if 
same  is  at  hand. 

In  the  front  of  the  boilers,  directly  beneath  the  drums,  galleries  are  provided  inter- 
connected to  all  other  boilers  in  the  same  row  to  facilitate  operation  and  repairs. 

A  superheater  of  672  square  feet  heating  surface  is  installed  in  each  boiler,  capable 
of  producing  a  temperature  of  150°  Fahr.,  which  would  mean  a  total  temperature 
of  530°  Fahr.  These  superheaters  are  of  the  Rosenthal  type,  as  manufactured  by 
the  Babcock  &  Wilcox  Company.  The  usual  arrangement  is  made  to  flood  these 
superheaters. 

Economizers. — As  practically  in  all  European  power  plants,  this  station  has  been 
provided  with  economizers.  Each  economizer  is  made  up  of  two  groups  of  tubes. 
There  are  eight  economizers  of  288  tubes  each,  and  twelve  consisting  of  576  tubes 
each.  The  total  heating  surface  of  this  economizer  plant,  which  is  of  the  Green  type, 
amounts  to  105,000  square  feet.  By  the  extension  of  the  plant,  eight  additional  288- 
tube  economizers  will  be  installed.  It  will  be  noticed  that  this  economizer  capacity 
is  an  extremely  large  one. 

Feed  Water.  —  The  basement  of  the  boiler  room  is  divided  into  three  sections. 
The  two  outer  sections  beneath  the  boilers  are  for  removing  ashes,  while  the  center 
one  beneath  the  fire  aisle  is  for  boiler-feed  pumps,  etc.  There  are  installed  eight 
vertical  simplex  compound  pumps  with  center  packed  plungers,  each  having  a  capacity 
of  18,000  gallons  (British)  per  hour. 


366 


STEAM-ELECTRIC   POWER   PLANTS. 


Feed  water  is  taken  from  a  storage  tank  located  in  the  oil-cooling  house  (see  Fig.  i). 
The  water  is  supplied  to  this  tank  from  an  8J-inch  artesian  well,  575  feet  deep.  Should 
this  well  fail  or  should  the  water  line  in  the  tank  become  low,  an  auxiliary  connection 
is  made  from  the  city  main,  provided  with  a  float  valve.  Besides,  this  further  pre- 


FIG.  4.     Interior  of  Generating  Room,  Chelsea  Plant,  London. 

caution  is  taken  by  installing  two  pumps,  which  have  their  suctions  connected  directly 
to  the  river.  As  all  of  these  feed-water  pumps  are  steam  driven,  the  exhausts  are 
brought  to  a  feed-water  heater. 

Chimneys. — There  are  four  radial  brick  chimneys,  having  a  diameter  of  19  feet 
and  being  253  feet  above  the  grates  of  the  lower  tier  of  boilers.  The  foundations 
are  42  feet  square  and  have  a  depth  of  34  feet  6  inches;  the  concrete  for  each  foundation 
amounts  to  2,000  cubic  yards.  The  smoke  may  pass  either  directly  through  the 
economizers  to  the  chimney,  or  may  be  by-passed,  in  which  case  it  passes  through 
a  flue  suspended  from  the  floors. 

Turbo-Generators.  —  The  turbo-generators  are  of  the  British  Westinghouse  type 
and  are  double  flow.  There  are  at  present  installed  eight  5,5oo-K.W.  units,  with  pro- 
vision for  two  similar  units,  and  one  of  2,7oc-K.W.  capacity.  The  turbines  are  direct 


CHELSEA  PLANT,    LONDON 


367 


connected  to  3-phase,  u,ooo-volt,  33^-cycle  revolving  field  generators,  operating 
at  1,000  revolutions  per  minute. 

The  turbines  are  designed  to  work  at  a  pressure  of  165  pounds  and  100°  Fahr. 
superheat,  and  permit  of  an  overload  of  50  per  cent,  with  a  vacuum  of  26  inches  and 
27  inches. 

The  guaranteed  steam  consumptions  of  these  turbines,  per  electrical  horse-power 
hour,  are  as  follows: 


Load. 

26" 

Vacuum  . 

27" 
Vacuum. 

....   6,87=;  K.W. 

1  6.0 

13.6 

Full  load                                                     .    . 

.    c  ,  soo      '" 

15  .6 

13.2 

.    .    .    .   4,125 

17.2 

15.0 

.     2,7?O        " 

18.4 

16.0 

The  guaranteed  electrical  efficiency  of  the  generators  on  non-inductive  load  is  as 
follows : 

Full  load 97-5°  Per  cent- 

Three-quarter  load 9^-5° 

One-half  load 95-°°         " 

One-quarter  load 90.00 

The  entire  turbo-generator  unit  is  48  feet  long,  n  feet  4  inches  wide  at  floor  level 
and  13  feet  9  inches  high  (above  floor);  the  turbines  have  an  overhanging  platform 
which  gives  a  total  width  of  17  feet. 

Piping.  —  Steam  is  drawn  from  the  boilers  through  6-inch  solid  drawn  mild  steel 
pipes,  eight  of  which  join  in  one  14-inch  pipe  header,  which  is  of  lap-welded  steel  from 
which  the  connections  are  run  to  the  turbines.  Besides  these  connections  there  is  a 
separate  auxiliary  header  of  lo-inch  pipe  connected  at  three  points  with  the  main 
steam  header.  The  6-inch  pipes  are  provided  with  screw  flanges;  the  lo-inch  and 
14-inch  are  provided  with  flanges  riveted  to  the  pipe.  All  flanges  are  of  forged  steel. 

Due  to  the  double  flow  type  turbine,  each  unit  is  provided  with  two  exhaust  out- 
lets of  44  inches  diameter,  while  the  atmospheric  exhaust  line  provided  with  a  relief 
valve  is  connected  to  a  riser  5  feet  in  diameter,  made  of  riveted  mild  steel,  with  cast- 
iron  tees  and  bends.  It  is  the  author's  opinion  that  instead  of  employing  a  6o-inch 
exhaust  riser,  a  30-inch  pipe  would  have  done  as  well,  for  the  liability  of  a  break-down 
of  several  condensers,  discharging  into  a  single  exhaust  riser,  is  doubtful,  and  in  modern 
practice  condenser  plants  should  be  installed,  so  that  one  may  figure  on  a  higher  degree 
of  reliability.  Taking  into  consideration  that  there  are  three  risers,  each  106  feet  long, 
and  that  the  cast-iron  bends  employed  weigh  not  less  than  7  tons  each,  it  will  readily 
be  seen  what  expense  this  involves. 


Condenser  Plant.  —  The  condensers  are  of  the  vertical  cylindrical  surface  type, 
having  a.  cooling  surface  of  15,000  square  feet  and  made  of  i-inch  tubes.     Each  tur- 


36S  STEAM-ELECTRIC   POWER   PLANTS. 

bine  has  its  own  condenser,  which  is  provided  with  a  20-inch  centrifugal  pump,  operated 
by  a  three-phase  motor,  and  as  the  top  of  the  condenser  is  some  29  feet  above  minimum 
low  water  after  the  circulation  has  been  established,  a  siphoning  action  takes  place. 
Each  condenser  is  further  provided  with  an  electrically  driven  dry  vacuum  pump,  and 
a  4- inch  electrically  driven  centrifugal  hot  well  pump.  The  water  of  condensation  is 
returned  by  means  of  the  latter  named  pump  to  the  feed-water  tank,  from  which  the 
boiler  feed  pumps  return  it  to  the  boiler.  The  vacuum  maintained  in  the  condensers 
is  about  27  inches.  The  only  additional  feed  water  necessary  is  that  which  is  consumed 
by  the  steam  driven  auxiliary  machinery,  leakage,  etc.  Considering  this,  and  also 
the  high  temperature  that  must  be  maintained  in  the  smoke  flue,  due  to  the  super- 
heaters, it  would  seem  that  the  economizers  were  needlessly  large,  as  the  heating  sur- 
face of  the  total  boiler  capacity  is  332,568  square  feet  and  that  of  the  economizers  is 
105,000  square  feet,  or  approximately  3  square  feet  of  boiler  surface  to  one  square  foot 
of  economizers. 

Exciters.  —  There  are  four  steam  driven  exciters  installed  at  the  east  end  of  the 
generating  room,  having  a  total  capacity  of  600  K.W.,  amounting  to  practically  i  per 
cent  of  the  present  plant  capacity.  The  engines  are  of  the  two-cylinder  compound 
enclosed  type,  running  at  375  revolutions  per  minute,  and  are  direct  connected  to 
the  generators  mounted  on  the  same  bedplate.  They  are  capable  of  withstanding 
a  25  per  cent  overload. 

Oil-Cooling  System.  —  A  separate  building  has  been  erected  for  cooling  and  filter- 
ing the  oil.  It  has  been  stated  that  each  turbine  requires  thirty-three  gallons  of  oil 
per  minute  to  circulate  through  the  four  bearings  of  each  turbo-generator  set,  amount- 
ing to  264  gallons  per  minute  for  the  eight  units.  This  building  is  some  50  feet  high 
and  contains  in  the  basement  and  ground  floor  three  oil  tanks,  while  the  third  floor 
accommodates  oil  filtering  and  gravity  tanks,  with  a  total  capacity  of  20,000  gallons. 
The  second  floor,  as  previously  mentioned,  is  occupied  by  the  feed-water  storage  tanks. 

Four  oil  mains  of  6  inches  diameter,  a  supply  and  a  return  having  a  head  of  30  feet, 
run  the  entire  length  of  the  basement.  The  oil,  after  passing  through  the  various  bear- 
ings, returns  by  gravity  to  the  oil- cooling  building,  whence  electrically  driven  centrif- 
ugal pumps  force  it  through  the  cooling  system  and  up  to  the  filtering  and  gravity 
tanks  located  on  the  top  floor.  This  practice  is  entirely  contrary  to  that  usually  em- 
ployed, as  it  is  natural  that  when  the  oil  is  hot  it  is  thinner  and  precipitation  of  foreign 
substance  is  much  more  easily  accomplished  than  with  cool  thick  oil;  in  fact,  oiling 
systems  are  installed  in  which  the  filtering  tanks  are  provided  with  steam  heating 
systems  to  facilitate  the  above-mentioned  precipitation. 

The  cooling  system  installed  in  the  Chelsea  plant  is  the  reverse  of  a  surface  con- 
denser. The  oil  is  forced  through  a  number  of  brass  tubes,  while  the  cooling  water 
drawn  from  the  Thames  surrounds  these  tubes.  There  are  three  of  these  installed, 
each  having  330  square  feet  of  cooling  surface.  The  total  working  capacity  of  this 
plant  is  350  gallons  per  minute. 


CHELSEA  PLANT,  LONDON. 


369 


Switching  Room.  —  As 
previously  stated,  a  space 
of  14  feet  is  set  apart  for 
the      switching    compart- 
ment, which  contains  four 
floors.      The   floor  in  the 
switching     room    on    the 
level  with  the  generating- 
room    floor    is   practically 
empty,  while    the    second 
floor,     ii    feet    6    inches 
above  this,  is  occupied  by 
the     main     generator    oil 
switches,    in    the   rear   of 
which  are   the  static  dis- 
charges, while  at  the  end  is 
the  auxiliary  switchboard. 
The  third  floor,  n  feet  6 
inches  higher,  is  the  main 
operating  floor.       A  plat- 
form   some    8    feet    wide, 
supported    by    brackets    ] 
from     the     crane     and 
switching-room     columns, 
overhangs    the   generating 
room.       This    platform 
contains      the      generator 
instrument  board  and  the 
controlling      bench,     and 
makes     the     entire    gene- 
rator   room   visible  to  the 
operator.      Directly  at  the 
back  of  the  gallery,  in  the 
switching  room  itself,  are 
the    feeder    panels,  in  the 
rear    of     which    are    the 
main     junction    switches, 
the  high-tension  generator 
bus-bars    passing    behind 
the  latter,  and  at  one  end 
are    the     motor    operated 
main  rheostats;  from  here 
the     leads      pass     to    the 
fourth     floor,    which    con- 


370  STEAM-ELECTRIC   POWER   PLANTS. 

tains  the  feeder  bus-bars  and  oil- feeder  switches  with  a  passage  between,  under  which 
the  high-tension  feeders  have  to  pass.  One  end  of  this  gallery  is  occupied  by  transformers. 
The  whole  switching  room  is  laid  out  with  ample  space,  but  the  arrangement  would 
certainly  be  improved  if  the  high-tension  feeders  did  not  have  to  pass  the  low-tension 
main  control  apparatus.  This  could  have  been  accomplished  by  placing  the  main 
bus-bars  on  the  main  generating-room  floor  level,  and  the  feeder  bus-bars  and  switches 
directly  above  on  the  second  floor,  leaving  the  controlling  boards  as  at  present  located. 
This  would  not  only  have  obviated  the  above-mentioned  difficulty,  but  would  have 
made  unnecessary  the  fourth  floor.  As  the  feeders  leave  the  building  in  the  tile  ducts 
beneath  the  basement  floor,  this  would  have  materially  simplified  the  switchboard 
arrangement,  and  would  have  avoided  the  carrying  of  the  feeders  some  40  feet  above 
the  generating-room  floor  and  back  again. 

Auxiliary  Electrical  Equipment.  —  As  the  entire  auxiliary  apparatus,  with  the  ex- 
ception of  the  boiler  feed  pumps  and  exciters,  is  motor  driven,  this  electrical  equip- 
ment is  of  particular  interest.  The  auxiliary  switchboard  consists  of  some  twenty- 
four  panels,  for  the  control  and  distribution  of  current  from  four  I25-K.W.  exciters, 
nine  single-phase  11,000  —  220-volt  transformers,  arranged  in  sets  of  three  (aggregating 
1,500  K.W.),  one  I25-K.W.  synchronous  motor  generator,  and  two  small  storage  batteries. 
From  this  board  current  is  supplied  for  89  three-phase,  220-volt  motors,  and  twelve 
i25-volt  continuous  current  motors.  The  total  capacity  of  these  units  is  nearly  2,000 
horse-power.  The  above-mentioned  motor  generator  consists  of  a  I25-K.W.,  220-volt, 
three-phase  synchronous  motor,  and  a  i25-volt  compound  wound  continuous  current 
generator,  used  for  charging  the  storage  batteries  and  supplying  continuous  current 
for  miscellaneous  purposes.  These  storage  batteries  supply  power  for  operating  the 
oil  switch  motors. 

Wiring  System.  —  As  will  be  seen  in  the  cut,  the  wiring  system  is  a  very  simple  one> 
and  has  been  laid  out  for  ten  main  generator  units;  the  two  main  generator  units  at 
the  left  hand  and  the  small  generator  unit  are  for  future  installations.  Contrary  to 
the  practice  in  most  modern  plants,  a  single  bus-bar  system  has  been  installed  instead 
of  a  double  bus-bar  or  ring  system,  bus  junction  or  sectionalizing  switches  being  in- 
stalled between  every  other  two  generators,  thus  giving  the  desired  flexibility. 

The  feeders  to  any  particular  sub-station  are  so  arranged  that  with  the  main  bus 
junction  switches  open,  current  is  drawn  from  different  generators.  This  is  a  very 
desirable  feature,  as  in  case  of  break-down  to  any  one  of  the  feeder  group  buses  the 
sub-station  supply  is  not  materially  affected. 

FJSK  STREET  PLANT,  CHICAGO. 

In  the  Fisk  Street  plant  an  entirely  new  arrangement  is  adopted,  it  is  claimed. 
This  is  the  placing  of  the  boiler  room  at  right  angles  to  the  generating  room.  This 
claim  is  not  quite  just,  since  as  early  as  1898,  Dr.  Kennedy  adopted  this  plan  for 
the  Edinburgh  McDonald  road,  as  has  already  been  pointed  out  in  Chapter  II,  on 
the  general  layout  of  power  plants,  and  it  is  old  English  factory  practice.  The  Fisk 


FISK  STREET  PLANT,   CHICAGO.  371 

Street  plant,  however,  being  the  first  prominent  steam  turbine  (Curtis)  plant,  has  been 
frequently  copied  in  recent  practice.  This  has  been  done,  not  for  any  saving  in  space, 
but  for  the  simpler  arrangement  of  piping  and  greater  reliability  of  operation  in  case 
of  failure  of  any  of  the  piping.  Besides  this,  better  light  and  ventilation  are  secured. 

The  Fisk  Street  plant  has  been  laid  out  for  some  14  turbines,  having  a  total  normal 
capacity  of  100,000  K.W.,  while  the  boiler  room  is  laid  out  for  112  boilers.  The  original 
equipment  of  this  station  consisted  of  four  5,ooo-K.W.  Curtis  turbine  units,  and  thirty- 
two  5oo-horse-power  Babcock  &  Wilcox  boilers.  There  have  been  added  four  9,000- 
K.W.  turbines  and  a  correspondingly  increased  boiler  capacity,  but  it  may  be  some 
years  before  the  ioo,ooo-K.W.  plant  is  completed. 

As  will  be  seen  from  the  accompanying  plan,  the  plant  is  located  very  favorably, 
directly  on  the  north  side  of  the  South  Branch  of  the  Chicago  River,  the  generating 
room  proper  forming  practically  the  foot  of  Fisk  Street.  The  plant  is  connected  with 
both  the  C.  B.  &  Q.  and  the  C.  &  A.  railways  by  sidings,  which  give  ample  facilities  for 
coal  and  ash  handling  as  well  as  building  material  and  machinery.  On  both  sides  of 
the  plant  are  two  canals,  running  parallel  with  the  plant,  Mason's  and  Allen's.  The 
condenser  water  is  drawn  from  the  former  and  is  discharged  into  the  latter.  It  will 
be  seen  that  this  is  almost  an  ideal  site  for  a  large  power  plant.  Large  coal  storage 
facilities  are  provided. 

A  separate  two-story  building,  460  feet  long,  has  been  provided  for  switching  pur- 
poses, and  runs  alongside  the  generating  room. 

Building.  —  The  entire  building  and  all  machinery  rest  upon  piles,  driven  down 
to  hard  pan  and  capped  with  concrete  foundations.  The  superstructure  embodies 
a  self-supporting  steel  skeleton;  the  walls  are  of  hard-pressed  red  brick,  giving  a  plain 
and  substantial,  but  very  pleasing  effect.  The  walls  of  the  generating  room  are  faced 
with  white  enameled  brick,  while  the  floor  is  laid  with  hexagonal  tile.  This  station, 
as  \vell  as  the  Boston  "L"  Street  station,  shows  marked  progress  in  the  architectural 
features  of  power  plants. 

The  generating  room  is  65  feet  wide  and  65  feet  to  the  top  of  the  roof  truss,  the 
crane  runway  is  50  feet  above  the  floor,  and  the  total  length  of  the  plant  when  com- 
pleted will  be  some  820  feet.  The  turbines  are  spaced  41  feet,  center  to  center. 
There  are  one  5o-ton  crane  and  one  6o-ton  crane  installed. 

On  both  sides  and  running  the  entire  length  of  the  generating  room  are  galleries, 
one  towards  the  boiler  room  to  facilitate  operation,  and  the  other  a  so-called  visitors' 
gallery. 

The  boilers  are  arranged  back  and  back,  leaving  5  feet  space  between  the  setting 
at  the  rear  as  well  as  at  the  side,  while  the  firing  aisle  is  29  feet  wide,  i.e.,  from  face  to 
face  of  boiler  setting.  The  basement  is  16  feet  high,  while  the  bottom  of  the  coal 
bunker  is  31  feet  6  inches  above  the  operating  floor,  the  bunker,  being  18  feet  6  inches 
deep,  is  practically  directly  below  the  roof  truss.  The  total  height  of  the  building 
from  the  basement  to  the  top  of  the  louver  is  75  feet.  Above  each  firing  aisle  is  run  a 
hand  crane  of  5  tons  capacity. 


372 


STEAM-ELECTRIC  POWER  PLANTS. 


CANAL 


1 

Q             ^ 

j 

PROPERTY  OF  THE  COMMONWEALTH 
a                                                            ELECIRIC  CO. 

FIG.  i.     Location  of  Fisk  St.  Plant,  Chicago  (Power). 


FIG.  2.     North  End  of  Fisk  St.  Plant,  Chicago. 


FISK   STREET  PLANT,   CHICAGO. 


373 


The  chimneys,  of  the  lined  steel  type,  are  carried  on  the  boiler  and  building  columns 
and  have  an  interior  diameter  of  18  feet,  and  a  height  of  205  feet  above  the  grates  for 
the  5,ooo-K.W.  units,  and  some  50  feet  higher  for  the  9,ooo-K.W.  units.  One 
chimney  serves  for  8  batteries  or  16  boilers. 

Boiler-Room  Equipment.  —  The  boilers  are  of  the  Babcock  &  Wilcox  make  and 
have  a  heating  surface  of  practically  5,000  square  feet  and  consist  of  2  drums  and 
252  tubes,  arranged  in  18  headers  of  14  tubes  each.  The  superheater  has  approxi- 


FIG.  3.     Firing  Aisle,  Fisk  St.  Plant,  Chicago. 

mately  900  square  feet,  and  is  guaranteed  to  produce  150°  Fahr.  superheat  under 
normal  working  conditions  and  gauge  pressure  of  180  pounds.  The  boilers  are  pro- 
vided with  chain-grate  stokers,  each  having  a  grate  surface  of  85  square  feet,  and 
are  belt  driven  from  a  shaft  operated  by  one  of  the  engines,  one  engine  operating  the 
grates  for  one  row  of  8  boilers,  the  other  engine  being  kept  in  reserve.  The  ashes 
are  dumped  directly  into  a  large  lined  ash  hopper,  suspended  from  the  structural  steel 
of  the  boiler  setting,  a  smaller  type  of  hopper  being  installed  immediately  in  front 
of  the  main  hopper  to  collect  the  fine  coal  falling  through  the  grates.  The  ashes  are 
carried  away  by  the  coal  bucket  conveyor  into  a  concrete  ash  hopper  at  the  end  of  the 
firing  aisle,  while  the  fine  coal  is  brought  back  to  the  coal  bunkers. 


374 


STEAM-ELECTRIC  POWER   PLANTS. 


Steam  Piping.  —  From  the  boiler  a  6-inch  steam  pipe  leads  at  the  rear  of  the  boiler 
in  the  basement  to  the  so-called  header  room,  where  the  main  and  auxiliary  steam 
piping  is  located.  The  main  header  varies  in  size  from  6  inches  for  a  single  boiler  to 
14  inches  for  a  row  of  boilers  of  8,  the  latter  being  the  size  of  the  main  to  the  turbine. 
The  steam  headers  are  so  interconnected  that  steam  may  be  drawn  from  adjoining 
boiler  rows.  In  this  header  room  there  are  also  placed  boiler  blow-off  piping  and  two 
boiler  feed- water  mains,  one  so-called  hot  feed  line,  and  the  cold  or  auxiliary  feed  line, 
the  latter  having  by-pass  connections  so  arranged  that  one  boiler  feed  pump,  which  is 


FIG  4      Smoke  Flues  and  Steam  Down-Takes,  Fisk  St.  Plant,  Chicago. 

placed  at  the  side  of  the  turbines  in  the  generating  room,  may  be  used  for  cleaning  the 
boilers.     All  these  pipes  are  of  wrought  iron,  with  ground  joint  welded  steel  flanges. 

Turbo-Generators.  — The  turbines  are  of  the  General  Electric  Curtis  type,  and 
were  the  first  5,ooo-K.W.  units  of  this  type  ever  built.  Owing  to  this  fact,  the  first  three 
turbines  are  of  the  2-stage  type,  while  the  fourth  unit  is  of  the  5 -stage  type.  They  are 
arranged  in  one  row,  each  having  a  separate  condenser.  Four  additional  units  of  9,000- 
K.W.  capacity,  each,  are  designed  with  a  so-called  base  condenser,  i.e.,  the  condenser 
frame  is  the  base  of  the  turbine.  These  latter  units  were  designed  for  only  8,000  K.W., 
but  during  tests  it  was  proved  that  they  developed  a  maximum  output  of  14,000  K.W. 


Cable  Tunnel  to  Switch  House 


FIG.  5.     General  Plan  of  Fisk  Street  Plant,  Chicago,  showing 


70'   Discharge  Canal  to  Riww 


riL    !. -..I— J:''CT~I 


four  5000-K.W.  Turbo-Generators  (Western  Electrician). 


FISK  STREET  PLANT,  CHICAGO. 


375 


-L  M        Li'*  -^ 


o 
_o 
U 

4-T 

a 


I-T   ' 

o 


376 


STEAM-ELECTRIC  POWER  PLANTS. 


FISK  STREET  PLANT,   CHICAGO. 


377 


and  a  very  efficient  operation  at  9,000  K.W.,  resulting  in  a  normal  rating  at  the  latter 
capacity. 

Condenser  Plant,  etc.  —  The  condensers  for  the  5,ooo-K.W.  units  have  a  cooling 
surface  of  approximately  20,000  square  feet  each,  and  although  they  are  compara- 
tively high,  being  placed  on  the  main  generating-room  floor,  they  occupy  a  large  amount 
of  space.  This  disadvantage,  however,  is  practically  overcome  by  placing  the  centrif- 


FIG.  8.     Interior  of  Generating  Room,  Fisk  St.  Plant,  Chicago. 
5000-K.W.  Curtis  Turbine. 

ugal  and  dry  vacuum  pumps,  which  are  operated  from  a  single  engine,  at  right  angles. 
At  the  side  of  the  condenser  are  also  placed  the  boiler  feed  pumps,  which  are  of  the 
single  cylinder  vertical  pattern.  For  each  boiler  row  of  5  boilers  there  are  2  feed 
pumps,  each  of  sufficient  capacity  to  take  care  of  the  entire  boiler  section. 

The  first  and  last  turbines  each  have  their  own  intake  tunnel,  the  others  being  sup- 
plied in  pairs.  The  5,ooo-K.W.  turbines  have  intake  tunnels  of  4  feet  and  4  feet  6  inches 
in  diameter,  while  the  9,ooo-K.W.  units  have  intake  tunnels  of  5  feet  in  diameter.  The 
water  flows  by  gravity  to  suction  wells,  placed  below  the  boiler  house  near  the  gener- 
ating room.  The  suction  line  for  the  centrifugal  pump  of  the  9,ooo-K.W.  units  is  42 
inches  in  diameter;  the  discharge  of  the  condenser  is  the  same  diameter.  For  the 


378 


STEAM-ELECTRIC   POWER   PLANTS. 


four  5,coo-K.W.  units  there  is  one  discharge  tunnel  leading  to  the  other  side  of  the 
power  house  to  the  Allen  Canal.  There  are  a  total  of  7  intake  and  3  discharge  tunnels, 
drawing  the  water  from  one  canal  and  discharging  to  the  other. 

The  hot  well  pumps,  which  are  of  the  centrifugal  type,  are  submerged  in  an  iron 
hot  well  some  4  feet  3  inches  in  diameter  and  9  feet  deep.  The  vertical  motors  are 
carried  above  the  floor  on  the  top  of  the  hot  well.  Directly  at  the  side,  well  grouped 


FIG.  9.     9000-K.W.  Curtis  Turbo-Generator,  Fisk  St.  Plant,  Chicago. 

with  the  other  apparatus  of  each  turbo-generator  set,  is  arranged  one  vertical  cylin- 
drical feed- water  heater,  some  18  feet  high.  Both  heater  and  hot  well  are  placed  in  a 
trench  some  9  feet  deep.  Each  turbine  is  provided  with  a  separate  36-inch  exhaust 
line  leading  beneath  the  generating- room  floor  to  the  boiler  house,  and  then  through 
the  roof.  Each  line  is  provided  with  an  atmospheric  relief  valve  near  the  condenser. 

Oiling  System.  —  A  large  steam  driven  oil  pump  maintains  the  circulation  of  oil 
for  the  step  bearings  at  1,200  pounds  per  square  inch.     There  are  also  installed  for 


FISK  STREET  PLANT,  CHICAGO. 


379 


Outgoing  Lines 


Turbo-Alternators 


FIG.  10.     Wiring  Diagram,  Fisk  St.  Plant,  Chicago. 

each  turbine  a  motor  driven  triplex  oil  pump,  and  held  in  reserve,  each  having  a  capa- 
city of  6  gallons  per  minute.  Accumulators  are  placed  in  the  boiler  room  to  main- 
tain a  constant  oil  pressure  in  case  of  temporary  disablement  of  the  oil  pumps.  As 
usual,  after  passing  through  the  bearings,  the  oil  is  filtered  and  used  over  again. 


FIG.  ii.     Engineer's  Office  and  Operating  Gallery,  Fisk  Street  Plant,  Chicago. 


380  STEAM-ELECTRIC   POWER   PLANTS. 

Electrical  Equipment.  —  The  generators  are  of  the  3-phase,  25-cycle,  9,ooo-volt 
revolving  field  type.  As  the  plant  is  arranged  on  the  unit  system,  the  generators  and 
other  electrical  apparatus  are  similarly  arranged;  provision,  however,  is  made  for  the 
operation  of  the  generators  in  multiple.  The  exciter  current  is  taken  from  the  main 
and  auxiliary  bus-bar. 

There  are  at  present  installed  three  5O-K.W.  motor  generator  sets  for  the  four  5,000- 
K.W.  units,  while  two  similar  units  are  proposed  for  the  new  9,ooo-K.W.  units.  In 


FIG.  12.     Switches  in  Switching  House,  Fisk  St.  Plant,  Chicago. 

addition  to  these  motor  driven  exciters  there  is  a  75-K.W.  steam  driven  exciter  and  a 
storage  battery  of  70  cells  with  a  one-hour  discharge  rate  of  800  amperes. 

Switching  Room.  — -  As  already  stated,  there  is  a  separate  two-story  building  for 
switching  purposes  560  feet  long  by  50  feet  wide,  and  50  feet  from  the  main  building. 
The  main  bus-bars,  high-tension  connections,  transformers,  manholes,  etc.,  are  placed 
in  the  basement  of  this  building,  while  the  high-tension  oil  switches,  instruments,  etc., 
are  on  the  first  floor.  The  main  oil  switches  are  controlled  from  the  generating  room ; 
centrally  located  in  the  main  generator  room,  and  above  the  visitors'  gallery  is  a  switch- 
board balcony.  From  here  the  entire  generator  room  may  be  easily  overlooked.  Only 


TWIN  MUNICIPAL  PLANT,  VIENNA.  381 

the  instruments  required  for  the  operation  of  the  plant  are  in  the  balcony,  the  over- 
load releases,  integrating  wattmeters,  transformers,  etc.,  being  in  the  switching  room. 

The  main  switchboard  in  the  switching  gallery  is  made  up  of  panels  5  feet  wide, 
there  being  one  panel  for  each  generator,  with  a  wattmeter  and  ammeter  in  each  of 
the  four  legs  of  the  generator,  a  voltmeter,  a  power  factor  meter,  a  frequency  indicator, 
a  field  ammeter,  and  exciter  voltmeter  mounted  on  each.  In  front  of  each  panel  is  a 
controlling  bench  for  operating  the  oil  switches,  provided  with  a  dummy  bus-bar 
system. 

Advantages  for  Employees.  —  For  the  benefit  of  the  employees,  this  plant  has  been 
provided  with  kitchen,  refrigerating  plant,  etc.,  as  follows: 

In  the  second  story  of  the  switch  house  are  locker  rooms,  wash  rooms,  lavatories 
and  shower  baths,  for  the  attendants  in  the  generating  and  switching  rooms;  a  similar 
equipment  has  been  provided  in  the  basement  of  the  boiler  room  for  the  boiler-house 
attendants,  with  good  light  and  ventilation.  In  the  switch  building,  second  floor, 
there  are  provided  bedrooms  for  the  temporary  use  of  those  having  special  duties. 
Here  are  also  a  kitchen  and  dining  room,  where  substantial  meals  may  be  had  at  small 
cost.  All  cooking,  etc.,  is  done  by  electricity. 

At  the  side  of  the  kitchen  is  a  2oo-pound  refrigerating  plant.  Also  on  the  same 
floor  are  an  assembly  and  reading  room,  where  all  important  engineering  periodicals 
are  on  file,  together  with  many  books  of  reference. 

It  will  be  seen  from  this  that  much  has  been  done  for  the  comfort  and  convenience 
of  the  employees.  This  was  the  more  necessary  since  there  are  no  restaurants  or 
boarding  houses  near  by,  and  it  is  undoubtedly  a  paying  policy  to  care  for  the  em- 
ployees in  this  manner.  It  may  sometimes  be  difficult  to  secure  a  good  operating  force, 
but  it  is  often  still  more  difficult  to  keep  it. 

TWIN  MUNICIPAL  PLANT,  VIENNA. 

For  supplying  the  City  of  Vienna  with  both  light  and  power,  and  for  operating 
railways,  both  in  the  city  and  suburbs,  two  power  plants  have  been  built  on  the 
Simmeriger  Heide,  the  nth  District  of  the  city,  directly  at  the  side  of  the  Danube 
Canal  and  the  Vienna  Interurban  Railway,  from  which  sidings  for  the  handling  of 
coal  and  ashes  have  been  run.  On  account  of  physical  difficulties,  two  separate 
plants  have  been  erected,  one  serving  for  light  and  power  for  the  city  and  private 
customers,  and  the  other  for  railroading.  These  plants  were  designed  by  the  same 
engineers  and  were  erected  and  put  into  operation  at  the  same  time;  it  is  fortunate 
that  the  frequency  of  the  generators  of  both  plants  was  chosen  the  same,  96  cycles 
per  second.  At  present  the  difficulties  have  entirely  disappeared,  and  the  two  plants 
operate  in  parallel,  so  that  current  for  light  or  power  may  be  drawn  from  either  of  the 
two  plants. 

On  account  of  the  above-mentioned  conditions  it  will  be  easily  seen  that  not  only 
the  first  cost,  but  also  the  operating  expenses  are  materially  increased. 


382 


STEAM-ELECTRIC   POWER   PLANTS. 


FIG.  i.     Twin  Municipal  Plant  of  Vienna,  Railway  Plant  at  the  Right. 


FIG.  2.     General  Plan  of  Twin  Municipal  Plant,  Vienna  (Engineering  Magazine]. 


TWIN  MUNICIPAL  PLANT,  VIENNA. 


383 


The  railway  plant  is  the  larger  and  has  been  designed  to  accommodate  eight  3,000- 
horse-power  horizontal  engines,  of  which  five  are  at  present  installed,  while  the  lighting 
plant  has  been  designed  to  accommodate  four  units  of  the  same  type  and  capacity. 

As  will  be  seen  from  Fig.  i  both  plants  are  placed  side  by  side  practically  in  the 
center  of  the  plot  and  surrounded  by  a  number  of  buildings;  viz.,  one  large  pump 
station  for  condenser-water  purpose  and  one  small  pump  station  for  boiler  feed,  an 
office  building  for  the  superintendent  and  his  staff,  a  superintendent's  residence 


FIG.  3.     Transfer  Table  for  Coal  Cars,  Vienna. 

and  a  building  for  the  main  operating  force.     Further  there  is  a  canteen  for  the  general 
staff,  as  the  plant  is  practically  isolated  from  the  city. 

As  will  be  seen  from  the  accompanying  plan,  the  general  arrangement  of  the 
two  plants  is  identical,  each  having  an  enclosed  coal  storage  building,  boiler  house, 
generating  house  and  a  switching  house.  The  coal  storage  plants  are  almost  side  by 
side,  being  separated  from  one  another  only  by  the  3-track  railroad  siding  referred 
to  above.  This  arrangement  was  made  to  facilitate  coal  handling.  The  coal  is  brought 
in  on  cars  on  this  siding,  and  carried  to  a  transfer  table  running  crosswise  to  either 
of  the  two  plants,  from  where  the  cars  are  brought  to  the  coal  storage  house.  Both 
plants  are  surrounded  on  three  sides  by  a  condenser  water  tunnel  in  the  shape  of  a  horse- 
shoe, and  are  fed  directly  from  the  Danube  Canal,  or  by  means  of  one  of  the  pumping 


384  STEAM-ELECTRIC   POWER   PLANTS. 

stations.  This  tunnel  is  built  to  serve  as  a  reservoir,  as  the  water  level  of  the 
Danube  Canal  varies  so  greatly  that  a  storage  of  water  was  found  to  be  necessary. 
As  has  been  stated,  the  largest  building  is  that  known  as  the  "railway  plant,"  while 
the  other  one  is  known  as  the  "lighting  plant,"  but  by  an  extension  of  these  buildings, 
which  will  be  found  to  be  necessary  in  the  near  future,  both  plants,  if  desired,  can  be 
made  of  equal  size.  In  order  to  give  a  still  better  water  supply  it  is  intended  to  run 
a  condenser  water  tunnel  around  the  whole  plant,  thus  forming  a  ring. 

For  unloading  machinery  a  structure  adjoining  the  two  buildings  has  been  erected, 
overspanning  the  railroad  sidings.  A  20-ton  electrically  operated  crane  unloads  the 
material  from  the  railroad  cars. 

The  buildings  composing  the  plant  are  well  grouped  and  well  designed  architec- 
turally. In  order  to  avoid  dust  as  much  as  possible,  they  are  surrounded  by  grass  plots 
and  gravel  walks,  while  a  number  of  shade  trees  are  scattered  throughout  the  lawns. 
A  high  picket  fence  encloses  the  whole.  The  entire  appearance  of  the  plant  is  most 
striking  and  is  a  very  good  example  of  European  power  plant  practice. 

Coal  Handling  System.  —  Coal  cars  of  15  to  20  tons  capacity  are  conveyed  to  a 
25-ton  transfer  table  of  special  construction,  which  takes  the  cars  to  an  additional 
siding,  leading  to  the  elevating  tower  of  the  coal  storage  building.  The  transfer 
table  receives  the  car  from  one  side  only  and  has  a  platform  of  6  wheels  over  3  rails, 
which  are  on  the  same  level  as  the  main  tracks,  from  which  the  car  is  received,  thus 
doing  away  with  the  usual  pit,  and  leaving  the  main  track  uninterrupted.  The  cars 
are  drawn  up  the  slight  incline  of  the  platform  by  a  lo-horse-power,  3oo-volt,  3-phase 
synchronous  motor.  This  motor  also  serves  to  propel  the  platform  to  the  required 
destination,  either  to  the  tracks  leading  to  the  coal  storage  building  of  the  railway 
plant  or  the  lighting  plant.  The  cars,  after  entering  the  coal  storage  building,  are 
elevated  by  a  300- volt;  35-horse-power,  3-phase  synchronous  motor  in  a  tower  above 
the  track  bins.  The  elevation  of  the  coal  cars  requires  two  minutes,  and  after  a  car 
has  reached  the  proper  height  an  automatic  brake  is  applied.  A  second  brake  will 
act  in  case  the  first  should  fail.  From  the  platform  of  the  elevator  the  cars  run  over 
a  steel  frame  structure  some  20  feet  above  the  coal  bins,  the  columns  of  which  are 
protected  by  wooden  covering  which,  at  the  same  time,  serves  as  a  part  of  the  compart- 
ment partitions.  There  are  10  compartments  or  bins  in  which  the  coal  is  dumped 
according  to  grade.  The  storage  capacity  is  sufficient  for  about  six  weeks.  Coal  is 
conveyed  to  the  boilers  in  small  three-wheel  cars  of  half  a  ton  capacity,  filled  and  moved 
by  hand  and  automatically  weighed  while  being  conveyed  to  the  boiler,  where  the  firing 
is  done  by  hand.  This  method,  while  not  the  most  recent  or  modern,  is  considered 
the  cleanest  and  most  economical.  The  cost  of  labor  is  considerably  increased  by 
this  plan,  but  as  each  car  of  coal  is  weighed  and  close  track  is  kept  of  the  ability  of 
the  stokers,  the  result  is  that  eventually  this  system  is  found  to  be  economical.  The 
same  arrangement  applies  to  both  railway  and  lighting  plants. 

Condenser  Water  Supply.  —  As  already  mentioned,  the  water  supply  for  the  rail- 
way plant,  as  well  as  the  lighting  plant,  is  very  elaborate.  Owing  to  the  fact  that  the 


M^S- --JJ -n -o-i P 

*S^^^^--~*=xip-«'«t-it::*1'J^d 


VorsUhtntU  Koten  tind  ISzagtn  auf  den 

0  Punkt  dft  Ptftls  bet  der  St.-E.-G.-Briieb 

16471. 


I  T 

iti 


FIG.  4.     Condenser  Water  Suppl 


-( — K-i-f4— -f— -  4 4— -4— 


y  System,  Municipal  Plant,  Vienna. 


TWIN  MUNICIPAL  PLANT,  VIENNA. 


385 


water  level  of  the  Danube  Canal  varies,  in  winter  falling  some  9  feet  below  and  in  the 
rainy  seasons  rising  some  12  feet  above  the  mean  water  level,  it  will  be  seen  that  it  was 
necessary  to  make  provision  to  meet  these  conditions. 

In  order  to  be  sure  of  an  uninterrupted  operation  of  both  plants,  irrespective  of 
unfavorable  water  supply,  one  large  pumping  station  for  elevating  the  water  from  the 
Danube  Canal  into  the  reservoir  tunnel  was  installed.  For  supplying  boiler  feed  water 
a  small  pumping  station  has  been  erected  and  four  wells  have  been  driven. 

The  accompanying  plan  shows  the  condenser  water  supply  system.  Referring  to 
the  lettering  in  this  plan,  the  screen  chamber  "K"  is  set  in  the  bank  of  the  Danube 


FIG.  5.     Motor  Drive  for  Condenser  Water  Supply  Pumps,  Vienna. 

Canal,  the  bottom  of  which  is  about  four  feet  below  the  canal  bed.  This  was  done 
in  order  to  maintain  a  practically  even  water  flow  throughout  the  intake  pipe.  The 
intake  chamber,  which  is  of  concrete,  i$  some  23  feet  in  length,  16.5  feet  wide  and  18.7 
feet  deep,  and  the  entire  screen  is  below  the  high-water  level.  After  the  water  has 
passed  the  rough  or  outside  screen  it  has  to  pass  a  fine  screen  in  order  to  enter  the 
second  chamber,  whence  it  enters  the  supply  pipe.  The  latter  is  48  inches  diameter 
and  is  fitted  with  a  sluice  gate.  From  here  the  water  is  let  into  the  main  well  "C," 
from  which  it  may  run  directly  into  the  reservoir  tunnel  through  the  pipe  "T,"  in 
which  case,  however,  the  water  level  of  the  Danube  Canal  is  to  be  above  that  of  pipe 


386 


STEAM-ELECTRIC  POWER  PLANTS. 


"T."  When,  however,  the  water  level  in  the  canal  is  below  this  point,  pumps  "P," 
in  the  large  pump  station  on  the  side  of  this  well,  have  to  elevate  the  water.  The  pres- 
ent pumping  station  is  designed  to  accommodate  four  pumps,  only  three  of  which  are 
in  place  at  the  present  time.  In  case  of  further  increase  in  the  capacity  of  the  power 
plants  it  will  be  necessary  to  increase  the  pumping  station  by  two  more  units.  For 


FIG.  6.     Condenser  Water  Supply  Pumps,  Vienna  (Engineering  Magazine). 

this  purpose  a  well  similar  to  "C"  must  be  installed,  as  will  be  seen  in  the  accompany- 
ing plan. 

Each  pump  has  a  capacity  of  865  United  States  gallons  per  second  and  is  capable 
of  lifting  water  23  feet  high,  which  will  easily  overcome  the  most  unfavorable  condi- 
tion which  may  arise.  The  present  pumps  have  a  total  capacity  of  2,595  United  States 
gallons  per  second,  or  about  30  per  cent  more  than  is  required  for  the  present  plant, 
and  it  will  be  seen  that  a  sufficient  storage  of  water  is  obtained  by  means  of  the  reser- 


FIG.  7.     Railway  Station  of  t 


;he  Twin  Municipal  Plant,  Vienna. 


TWIN  MUNICIPAL  PLANT,   VIENNA.  387 

voir  tunnel.  The  pumps  are  of  the  vertical,  4- plunger,  single-acting  type,  18  inches  in 
diameter,  having  a  stroke  of  24  inches,  and  making  60  revolutions  per  minute.  Two 
plungers  operate  from  a  single  crossbeam  which  is  driven  by  a  75-horse-power,  3-phase 
motor.  In  order  to  do  its  own  priming  the  pump  is  provided  with  an  additional  small 
vacuum  cylinder,  operated  from  the  main  levers. 

While  the  pumps  are  located  in  the  basement  of  the  station,  the  motor  is  on  the  main 
operating  floor.  By  means  of  a  rheostat  the  speed  may  be  reduced  from  60  to  40 
R.P.M. 

The  reservoir  tunnel  has  a  width  of  6  feet  and  a  depth  of  163  feet,  and  when  both 
plants  are  completed  this  tunnel  will  have  a  total  length  of  2,300  feet,  and  will  hold 
1,663,000  United  States  gallons. 

Boiler  Feed- Water  Supply.  — As,  at  the  time  of  the  erection  of  this  plant,  the  sewage 
system  of  the  city  was  discharged  into  the  Danube  Canal  ahove  the  power  plants,  the 
water  was  unfit  for  boiler  feed  purposes,  and  as  the  city  authorities  would  not  allow 
water  to  be  drawn  from  the  city  mains  beyond  a  certain  quantity,  wells  were  driven 
so  as  to  give  an  adequate  supply.  This  water,  however,  had  to  be  softened,  as  will  be 
seen  later  on.  There  are  four  wells,  situated  some  distance  from  the  canal,  and  from 
these  the  water  is  drawn  by  means  of  pumps  in  a  small  pump  station.  In  this  station 
are  installed  two  motor  driven  rotary  piston  pumps,  having  a  total  capacity  of  450 
gallons  per  second.  From  here  the  water  is  pumped  to  the  river  water  basin  near  the 
boiler  house,  whence  it  is  pumped  to  a  water-purifying  system.  This  river  water  basin 
may  also  collect  the  condenser  water  discharge,  in  case  the  boiler  feed- water  supply 
should  fail.  This  source  of  supply,  however,  cannot  be  taken  advantage  of  under 
present  conditions,  and  not  until  such  time  as  the  sewage  discharge  is  placed  below 
the  condenser  water  intake. 

The  water  supply  systems  herein  described  apply  (as  did  the  coal  handling  system) 
to  the  lighting  plant  as  well  as  to  the  railway  plant. 

As  both  plants  have  been  designed  on  the  same  lines,  it  will  suffice  to  describe  the 
railway  plant  only,  the  only  noticeable  difference  between  the  two  being  that  the  light- 
ing plant  contains  fewer  units. 

Railway  Power  Plant.  —  This  plant  consists  of  a  coal  storage  room,  a  boiler  room, 
a  generating  room  and  an  annex  for  switching  purposes,  etc.  There  are,  in  fact,  four 
different  buildings  separated  by  partitions.  With  the  exception  of  the  switching  room, 
which  is  165  feet  long  by  30  feet  wide,  all  three  buildings  have  the  same  length,  i.e., 
510  feet.  The  width  of  the  coal  storage  room  is  50  feet,  that  of  the  boiler  room  100 
feet,  and  that  of  the  generating  room  85  feet. 

The  appearance  of  the  plant,  and  especially  that  of  the  generating  room,  is  of  pleas- 
ing effect.  As  may  be  seen  in  the  accompanying  illustration  the  floor  is  tiled,  while 
the  light  and  ventilation  are  well  taken  care  of,  there  being  a  number  of  roof  ventilators 
(small  towers)  as  well  as  large  windows  throughout  the  building. 

Boiler  Room.  — •  The  boilers  are  banked  on  each  side  of  a  wide  aisle,  arranged  two 
to  a  battery,  there  being  at  present  20  boilers  of  the  Babcock  &  Wilcox  pattern,  made 


388 


STEAM-ELECTRIC   POWER  PLANTS. 


I 


00 

d 


TWIN  MUNICIPAL  PLANT,  VIENNA. 


389 


by  the  "  Ersten  Bruenner  Maschinen  Fabrik,"  Austria.  They  are  each  of  3,075  square 
feet  heating  surface,  and  operated  at  a  pressure  of  215  Ibs.  per  square  inch.  Four  of 
these  boilers  supply  steam  to  one  3,ooo-horse-power  engine.  Each  boiler  consists  of  two 
drums  23  feet  long,  42  inches  dia.  and  14  X  8  tubes.  The  lower  horizontal  headers, 
consisting  of  22  tubes,  are  connected  to  the  vertical  headers  by  means  of  short  tubes, 
while  four  longer  ones  connect  each  header  directly  to  the  boiler  drum.  This  is  done 
to  increase  the  circulation  of  water  in  the  lower  row  of  tubes.  In  addition,  in  each  boiler 
drum  is  installed  a  Dubian  artificial  circulating  apparatus,  by  which  the  generation  of 


FIG.  9.     Interior  of  Boiler  Room,  Vienna  (Electrical  J\evieiv}. 

steam  is  increased,  it  is  claimed,  from  3  pounds  per  square  foot  heating  surface  to 
4  pounds  and  higher.  Steam  and  water  passing  up  through  the  headers  with  great 
velocity  pass  through  the  vertical  tubes  of  the  system,  which  project  above  the  high-water 
level  in  the  drum,  thus  greatly  accelerating  the  circulation  and  evaporation.  It  will 
be  noticed  that  these  boilers  are  not  equipped  with  a  mud  drum,  although  two  2  J-inch 
blow-off  pipes  are  provided  at  the  vertical  header,  a  practice  which  is  commonly  found 
in  Europe  where  water-purifying  systems  are  installed.  Between  the  water  tubes  and 
the  drums  is  arranged  a  superheater  of  575  square  feet,  which  will  increase  the  steam 
temperature  to  570°  Fahr.  The  boilers  are  equipped  with  hand-fired  grates  of  87.5 
square  feet  surface,  while  above  the  fire  doors  steam  jets  are  provided  for  better  smoke 


390 


STEAM-ELECTRIC   POWER   PLANTS. 


TWIN  MUNICIPAL  PLANT,  VIENNA. 


391 


consumption.  In  addition  to  this  the  fire  wall  is  provided  with  air  ducts  admitting 
air  from  the  ash  pit  directly  above  the  furnace. 

The  ash  and  soot  pits  are  of  brickwork,  the  fire  bridge  being  provided  with  suitable 
openings  equipped  with  sliding  doors. 

Feed  Water.  —  In  the  rear  of  the  boiler  in  the  basement,  Green  economizers  are 
installed.  The  cleaning  of  the  tubes  is  accomplished  by  electrically  operated  scrapers. 
For  every  two  boilers  (or  battery)  there  is  installed  one  economizer.  The  tempera- 
ture of  the  water  in  the  economizer  is  raised  to  212°  Fahr. 

Four  Worthington  compound  boiler  feed  pumps,  working  upon  a  ring  pipe  system, 


FIG.  ii.     Reisert  Water  Purifiers,  28.000  cu.  ft.  hourly  capacity,  Municipal  Railway 

Plant,  Vienna. 

furnish  the  necessary  water.  The  pipes  are  arranged  so  as  to  easily  by-pass  the  econo- 
mizer and  feed  directly  into  the  boilers.  In  order  to  do  so,  however,  the  water  is  pre- 
viously heated  by  the  exhaust  steam  of  the  boiler  feed  pumps.  The  hot-water  storage 
tank,  containing  a  set  of  coils,  is  located  on  the  boiler-room  floor. 

At  one  end  of  the  boiler  house  are  installed  two  water  purifiers.  They  are  of  the 
Hans  Reisert  system  and  have  an  hourly  capacity  of  1,050  United  States  gallons.  The 
river  water  is  taken  out  of  a  reservoir  in  the  basement  and  pumped  by  means  of  two 
Voith  compound  pumps  into  a  tank  above  the  purifying  plants.  After  the  water  has 


392  STEAM-ELECTRIC   POWER   PLANTS. 

been  softened  in  the  purifiers  to  5  English  degrees  it  is  collected  in  the  above-men- 
tioned hot-water  tank  on  the  boiler-room  floor. 

Chimneys.  — At  the  end  of  the  plant  are  two  chimneys  with  ornamental  brickwork. 
The  internal  diameter  at  the  top  is  12.5  feet;  the  height  is  205  feet  above  the  furnace. 
For  a  height  of  30  feet  the  chimneys  are  lined  with  fire  brick.  The  foundations  are 
of  hydraulic  concrete  mixed  1:3:7,  while  the  lowest  layer  is  a  mixture  of  1:3:^. 
This  mat  has  a  thickness  of  4.7  feet  and  is  49.2  square  feet  in  area,  reinforced  by  a 
grillage  of  "I"  beams.  The  entire  weight  of  the  chimney,  which  is  of  radial  brick, 
with  the  exception  of  the  base,  is  3,800  long  tons,  1,450  tons  of  which  is  the  weight  of 
the  foundation. 

Steam  Piping. —  A  5-inch  pipe,  which  is  provided  with  a  non-return  valve,  leads 
from  each  boiler  or  superheater.  As  four  boilers  supply  steam  to  one  engine,  these 
pipes  are  connected  to  one  main  header  8  inches  in  diameter.  These  pipes  are  of 
Mannesmann  process,  long  sweep  bends  taking  up  the  expansion  and  contraction.  The 
main  header,  which  is  suspended  from  the  building  structure,  leads  toward  the  division 
wall  of  the  boiler  and  generating  room, where  it  runs  down  below  the  boiler-room  floor 
in  the  basement  and  thence  to  the  engine.  This  latter  end  of  the  steam  pipe  is  in- 
creased to  a  diameter  of  18  inches,  in  order  to  act  as  a  small  reservoir,  which  is  neces- 
sary on  account  of  the  small  steam  pipe.  Before  the  pipe  is  connected  to  the  valve 
chest  of  the  cylinders  a  small  separator  is  provided  for  the  purpose  of  drawing  off  any 
water  which  might  be  present.  The  tongue  and  groove  joint  system  of  flanges  has 
been  adopted  throughout  the  entire  plant.  In  order  to  insure  safe  operation  the  adja- 
cent steam  headers  are  interconnected.  All  high-pressure  pipes  are  covered  with 
Thermalite,  a  very  efficient  insulating  material. 

Engines.  —  There  are  at  present  five  3,ooo-H.P.  engines  installed,  manufac- 
tured by  the  "  Ersten  Bruenner  Maschinen  Fabrik  "  after  the  pattern  of  the  well- 
known  Sulzer  Bros.  These  engines  are  of  the  four-cylinder,  triple-expansion,  vertical 
type,  developing  at  175  pounds  pressure,  90  revolutions  per  minute,  3,000  nor- 
mal H.P.  or  3,600  maximum  I.H.P.  The  engine  is  made  up  of  one  high- 
pressure  cylinder  31.5  inches  in  diameter,  one  intermediate  cylinder  of  46  inches 
diameter  and  two  low-pressure  cylinders  each  of  68  inches  in  diameter,  the  common 
stroke  being  59  inches.  As  the  cylinders  are  arranged  in  tandem  form,  the  two  low- 
pressure  cylinders  are  nearest  the  shaft.  This  is  done  to  prevent  the  unnecessary 
heating  of  the  generator  by  the  high-pressure  steam  cylinder.  The  cylinders  are 
arranged  on  a  bedplate  to  allow  for  expansion,  which  amounts  at  the  end  of  the  high- 
pressure  cylinders  to  f  of  an  inch.  All  cylinders,  with  the  exception  of  the  high-pres- 
sure cylinders,  are  steam  jacketed. 

Each  cylinder  is  provided  with  4  four-seated  poppet  valves  and  the  entering  steam 
is  controlled  by  a  Sulzer  governor,  of  such  delicacy  that  by  throwing  off  the  entire  load 
the  variation  in  speed  is  only  4  per  cent.  For  the  purpose  of  throwing  the  different 


TWIN  MUNICIPAL  PLANT,  VIENNA. 


393 


generators  in  parallel  these  governors  are  equipped  with  small  electric  motors  operated 
from  the  switchboard. 

The  cranks  are  placed  at  108°.  The  poppet  valves  are  operated  by  bevel  gears  pro- 
vided with  expansion  couplings.  Each  cylinder  is  provided  with  an  oil  pump,  while 
for  oiling  the  crank  pins,  cross-headers,  etc.,  a  central  oiling  system  is  used.  Beneath 
each  crank  in  the  basement  is  placed  a  wet  jet  condenser  outfit.  The  pumps  are 
operated  by  means  of  a  rocker  and  hollow  rod  from  the  main  crank  pins.  T  he  stuffing 
boxes  of  the  pumps  are  water  sealed  in  order  to  maintain  a  good  vacuum.  1  he  engines 


FIG.  12.     Generating  Room,  Vienna  Plant. 


are  guaranteed  at  a  pressure  of  175  pounds  with  a  steam  temperature  of  from  500° 
to  575°  Fahr.  to  consume  not  more  than  10  pounds  per  I.H.P.  hour.  The  weight 
of  each  engine  without  generator  is  245  long  tons  and  its  cost  250,000  kronen  or 
$50,000.  The  foundation  of  each  unit  consists  of  1,040  cubic  yards  concrete  and 
costs  41,000  kronen  or  $8,200. 

Generators.  —  Between  the  cylinders  upon  the  shaft  is  mounteda  2,ooo-K.W.  3-phase 
generator.  The  stationary  part  is  made  up  of  4  cast-iron  pieces,  each  28.8  feet  in 
diameter,  31  inches  wide.  The  magnetic  field  is  provided  with  384  slots  and  for 
properly  insulating  the  coils,  mica  tubes  are  used.  The  rotating  part  of  the  gen- 


394 


STEAM-ELECTRIC   POWER   PLANTS. 


erator  weighs  43  long  tons.  The  fields  are  excited  by  220-volt  direct  current.  At 
90  revolutions  per  minute  the  frequency  is  96.  The  voltage  is  5,500,  normal  load 
2,000  K.W.,  while  2,500  K.W.  may  easily  be  developed. 

Exciters.  —  In  the  front  of  the  switchboard  there  are  at  present  three  22O-volt  exciter 
generators,  direct  connected  to  5, 500- volt,  3-phase  motors.  Each  set  has  a  capacity 
of  65  K.W..  which  will  suffice  to  excite  two  of  the  main  generators.  So  as  to  insure  a 


FIG.  13.     Switchboard  and  Exciter  Units,  Vienna. 

safe  operation  in  case  of  emergency  and  to  allow  for  fluctuation  in  the  load  a  storage 
battery  is  installed. 

Crane,  etc.  —  The  generating  room  is  equipped  with  a  4o-ton  electrically  operated 
crane,  with  a  span  of  84.6  feet.  The  trolleys  are  provided  with  three  motors,  8, 
ii  and  15  H.P.  In  place  of  the  wire  cables  usually  employed  in  connection 
with  a  crane,  a  Gall's  chain  is  used.  The  movement  of  the  crane  is  50  feet  per 
minute,  while  that  of  the  trolley  is  30  feet  per  minute.  A  load  of  20  tons  may  be  hoisted 
3.3  feet  per  minute,  while  40  tons  (or  a  full  load)  requires  double  that  time.  The  crane 
body  itself  is  a  lattice  girder  design,  which  is  much  favored  on  the  Continent  of  Europe. 

Switchboard. — The  switchboard  is  of  ornamental  design  and  separates  the  switch- 
ing building  from  the  main  generating  room.  This  switching  building  consists  of 


TWIN  MUNICIPAL  PLANT,  VIENNA. 


395 


several  floors  and  contains,  besides  the  rooms  occupied  by  the  electric  equipment,  a 
measuring  room,  a  storage  room,  repair  shop  and  offices.  The  space  occupied  by 
electric  equipment  is  divided  into  three  sections  for  three  separate  purposes,  one  to 
contain  the  generator  leads,  one  the  outgoing  feeders,  while  the  third  is  used  for  the 
exciter  current.  Sections  i  and  2  contain  two  bus-bar  systems,  so  arranged  that  all 
generators  may  be  thrown  in  parallel  on  the  outgoing  feeders.  Between  the  generator 


FIG.  14.     Rear  of  Switchboard  on  Main  Generating  Floor,  Vienna. 


leads  are  installed  sectional  lighting  switches.  The  switchboard  itself,  according 
to  European  practice,  is  faced  with  marble  slabs  mounted  upon  an  iron  structure.  It 
is  two  stories  high.  The  apparatus  required  for  each  generator  and  outgoing  feeder 
has  its  own  panels.  Such  a  panel  consists  of  a  voltmeter,  ammeter  and  recording 
wattmeter,  high-tension  switches  and  fuses,  and  further  necessary  equipment  for 
exciter  current  and  synchronizing  the  generator.  The  upper  part  of  the  switchboard, 
which  is  served  from  the  gallery  in  front  of  it,  is  for  the  outgoing  feeders  exclusively. 
For  operating  the  various  pumps,  cranes,  etc.,  two  transformer  groups  are  installed 
in  the  basement  of  the  switching  building,  near  which  the  storage  battery  is  placed. 
The  transformers  are  of  the  oil-cooled  types,  150  K.W.  and  will  reduce  the  voltage 
from  5,500  volts  to  300;  two  other  small  transformer  groups  reducing  the  voltage  to 


396 


STEAM-ELECTRIC  POWER   PLANTS. 


rt 

Sc 


TWIN    MUNICIPAL    PLANT,    VIENNA. 


397 


no  serve   for  lighting.     In  case  of  the  failure  of  the  3-phase  current  arrangement, 
provision  is  made  for  lighting  by  direct  current  from  the  storage  battery. 

Tests.  —  The  operation  of  this  plant,  as  well  as  that  of  the  lighting  plant,  is  a  most 
economical  one.  The  operating  results  of  these  plants  are  given  in  the  accompanying 
table,  showing  the  manufacturers'  guarantee,  and  the  operation  of  the  generating  unit 
of  the  railroad  power  plant,  with  its  boilers,  etc.,  as  well  as  that  of  the  generator  unit 
No.  2  of  the  lighting  plant. 

It  will  be  noticed  that  the  steam  consumption  in  the  latter  plant  is  9.4  pounds 
per  I.H.P.  hour,  while  the  coal  consumption  is  1.3  pounds.  Especial  attention 
should  be  called  to  the  fact  that  the  total  heating  value  of  the  coal  for  producing  i  horse- 
power hour  amounts  only  to  16,093  B.T.U.  The  cost  of  producing  one  K.W.  hour 
at  the  bus-bar  is  0.36  (1.8  heller),  the  above-mentioned  coal  costing  $3.60  (18  kronen) 
per  long  ton.  This  economical  result,  frequently  obtained  in  European  power  plants, 
is  not  only  due  to  the  manufacturers'  guarantee  or  the  efficiency  of  the  operating 
force,  but  also,  to  a  large  extent,  to  the  wise  selection  and  proper  arrangement  of 
the  machinery  to  be  used,  on  the  part  of  the  power  plant  designer. 


TABLE  OF   GUARANTEE  AND  TESTS   OF  THE  RAILWAY  AND  LIGHTING  PLANTS 

OF  VIENNA. 


SUBJECT. 

Guaranteed 
Results 
by  the 
Builders. 

Actual  Results  of  Test 
of  Engine  Units. 

No.  4  of 
Railway 
Plant. 

No.  2  of 

Lighting 
Plant. 

P^vaporation  of  water  per  sq.  ft.  heating  surface  per  hour,  in  Ibs.  . 
Evaporation  of  water  per  Ibs.  of  coal  from  feed  water  at  32°  Fahr. 
in  Ibs  

3 

7-i 

70 
11,697 

2,000 
82.7 

10.  1 

2.42 
12,870 
2,500 

3-45 

7-5° 
71.80 

12.137 
7.60 
4.80 
3.320 
2,091 
85.6 

IO.I 

1-43 
2.28 
12,584 
2,600 

3-3° 

7-5 
72.80 
12,177 
8.30 
4.80 
3,388 
2,086 

837 
9.41 
1.32 

2.  II 
",723 

2.55° 

Total  efficiency  of  boiler  in  per  cent     

Calorific  value  of  coal  per  Ib.  in  B.T.U  
Efficiency  of  economizer  in  per  cent     •.    . 

Efficiency  of  superheater  in  per  cent     

Indicated  horse-power  of  steam  engine     

Output  of  generator,  excl.  exciter,  in  K.W  .    . 

Efficiency  of  generator  unit  in  per  cent    .... 

*  Steam  consumption  per  one  H.P.  hour  in  Ibs  

Coal  consumption  per  one  H  P.  hour  in  Ibs  

Coal  consumption  per  K  W   hour  in  Ibs      

Coal  consumption  per  K.W.  hour  in  B.T.U  
Overload  of  generator  in  K  W                        

*  Steam  pressure  175  Ib.,  temperature  570°  Fahr.  (at  throttle). 


CHAPTER    XI. 

THE  following  tables  show  the  principal  dimen- 
sions and  other  data  of  turbine  and  reciprocating 
engine  plants.  The  sizes  and  capacity  of  these 
plants  vary  from  4,000  K.W.  to  60,000  K.W.;  the 
sizes  of  the  individual  prime  movers  vary  from  2,000 
K.W.  to  5,000  K.W.  It  is  the  author's  opinion 
that  it  is  not  necessary  to  give  data  on  smaller 
sizes  of  plants,  as  Chapter  IX  has  been  devoted  to 
this  subject.  There  are  also  a  series  of  tables  on  the 
equipment  of  plants  per  K.W.  These  figures  vary 
and  it  will  be  seen  cannot  be  blindly  followed, 
but  comparison  may  be  made  and  conclusions 
drawn  therefrom. 

Between  the  various  tables  illustrations  are  inserted 
which  speak  for  themselves. 


398 


POTOMAC  PLANT,  WASHINGTON,  D.C. 


399 


SUBJECT. 

REMARKS. 

BUILDING                         

Hollow  concrete  blocks. 
Two  firing  aisles. 
At  right  angle  to  boiler  room. 
Annex. 

Boiler  room             

164'  X  120'        

Generating  loom    

164'  X  41?' 

Switching  room              

164.'  X  i<;' 

24  B    &  W 

At  present  installed  

16             

In  four  rows. 

6,040  sq.  ft  

17?    Ibs 

i  185  sq.  ft.                   

150°  Fahr. 
Roney  stokers. 
6"  auxiliary  header. 

Grates                                      •    •    • 

1  1  1.  8  sq.  ft.          

STEAM  PIPING                      .... 

7"  at  boiler,  15"  header    .... 
Open  type 

FEEDER  WATER  HEATERS  (2)    .    . 

200,000  Ibs.  from  80°  to  205°  Fahr. 
16"  X  ioj*  X  1  6*                   .    .    . 

Per  hour. 
Horizontal  duplex. 
Future. 

FEED  PUMPS  (2) 

"           "       d) 

1  6"  X  10-^"  X  1  6"          

STORAGE  TANKS    (2) 

HOUSE  PUMPS  (2)                    ... 

7$"  X  10"  X  10"    

Horizontal  duplex. 
One  for  8  boilers. 

CHIMNEY   (3)                         .... 

Concrete  steel     

183'  o" 

Internal  diameter  at  top      .    .    . 
COAL  HANDLING 

12'  o" 

i  locomotive  crane 

Steam  driven. 
15  horse-power  motor  per  set. 
Crushers,  25  horse-power  each. 
6  tons  per  lineal  ft. 
To    bucket    conveyor;    reinforced 
concrete  hoppers. 

Concrete,    part    of    turbine    foun- 
dations. 
G.  E.  Co.  Curtis. 

Conveyors               

2  bucket  and  2  belt  conveyors    . 
40  tons  per  hour    

Bunkers  (2)                

650  tons       

ASH  HANDLING 

Industrial  railway 

CIRCULATING  WATER. 
Intake                                  .... 

40  sq.  ft  

Outlet                               

40  sq.  ft  

TURBO-GENERATORS  (2)      .... 
(2)      .... 
(i)      .    .    .    . 
Speed                          .        .... 

2,000  K.W.  each   
5  ooo  K.W.  each           

5,000  K.W.  each   

Future. 

750  R.P.M  

•3-nhase.  2?-cvcle 

4  poles. 

Volt 

6  600 

CONDENSERS 

Base  condensers                 .... 

Size                                     .... 

5,000  K.W.  =  20,000  sq.  ft.     .    . 

2  ooo  K  W^  —     8  ooo       " 

CIRCULATING  PUMPS    

5,000  K.W.  =  24-inch  centrifugal 
2,000  K.W.  =  i6-inch 
Rotative   single-stage 

Steam  driven,  horizontal. 

Motor  driven,  vertical. 
Steam  driven,  horizontal. 
Horizontal. 
Future. 
Auxiliary  pump. 
Future. 
600  gal.  per  hour,  each. 
50  feet  above  generator  floor. 

DRY  VACUUM  PUMP 

HOT  WELL  PUMP 

Two-stage    centrifugal 

EXCITERS  (2)    

100  K.W.,  125  volts  

OIL  PUMPS  (3)  

o"  X  •?!"  X  io* 

(i)     ........ 

o"  X  T&"  X  io* 

"       (i). 

6"  X  4"    X    6"      

(i)  

6"  X  4"    X    6"      

TANKS  (2)      

filtering  tanks 

CRANE  (i)     

50  ton  (io  ton  aux.  hoist)    .    .    . 
42'  o" 

SPAN                                           .    . 

4<x> 


STEAM-ELECTRIC   POWER   PLANTS. 


FIG.  i.     5000-K.W.  Turbo-Generator,  Condenser  Plant  and  Heaters,  L  St.  Plant,  Boston. 


FIG.  2.     Interior  of  Boiler  Room,  L  St.  Plant,  Boston, 


L  STREET  PLANT,   BOSTON. 


4OI 


402 


STEAM-ELECTRIC   POWER   PLANTS. 


02 
•J 


O 

m 


L  STREET  PLANT,  BOSTON. 


403 


404 


STEAM-ELECTRIC   POWER  PLANTS. 


L  STREET  PLANT,   BOSTON. 


405 


FT  j 


FIG,  7.     Plan  and  Elevation  of  one  5ooo-K.W.  Turbo-Generator  Unit  with  Auxiliaries, 

L  Street  Plant,  Boston  (Power}, 


406 


STEAM-ELECTRIC  POWER  PLANTS. 


59TH  STREET  PLANT,  NEW  YORK. 


SUBJECT. 

REMARKS. 

BUILDING    

693'  9"  X  200'  10"    

Boiler  room    

6oV  o"  X    8V    o"    . 

Coal  bunker,  11,500  tons. 
Including  switch  room,  23  ft.  wide. 
One  tier. 
One  tier. 
Each. 

Generating  room 

693'  9"  X  117'  10"    . 

BOILERS  (72)         

B.  &  W     

At  present  installed  

60     

Size                                        , 

6,008  sq.  ft.     .    . 

Pressure  

200  Ibs  

Grates,  incline  type  
Grates,  hand  fired     

iii.S  sq.  ft.  (42)    
100      sq.  ft.  (18)    
768     sq.  ft.  (8) 

Natural  draft. 
Forced  draft. 
For  turbine. 
Exclusively. 
Three  10"  equalizing  system. 
Two  15"  to  one  engine. 
Separate  tier,  above  boilers. 

Superheater    

Superheater    

900      sq.  ft.  (4)      
9",  18"  O.D.  header      

Steam  pipe  connection     .    .    . 

ECONOMIZER  (14)  
Heating  surface 

Sturtevant   

107,600  sq.  ft. 

Feed  pumps   

Tanks. 
One  for  12  boilers. 
Natural  draft  and  forced  draft. 

CHIMNEYS  (5)   

Radial  brick       

Height  above  grate  

218'  o"     

Diameter  at  top    

1  6'  o"  

COAL  HANDLING  SYSTEM   .    .    . 
Capacity      

Movable  tower  

Steam  driven. 

Motor  driven. 

ii            a 
Storage  battery  locomotive. 

Concrete. 
Concrete. 
Hor.  ver.,  cross  compound. 
Hor.  ver.,  cross  compound. 

200  tons  hour;  ij  tons  bucket     . 
Fixed  tower    

System             .                . 

Capacity      .        

150  tons  hour;  i  ton  bucket    .    . 
30"  and  20"  belts  

Conveyor                     .    . 

ASH  HANDLING  SYSTEM      .    .    . 

CIRCULATING  WATER. 
Intake 

Industrial  railway      

82  sq.  ft. 

Outlet                              .        .    . 

7o  sq.  ft. 

ENGINES  (A)  (n)     

7,500  I.H.P.,  each     

At  present  installed  (9)    ... 
Pressure 

7  500  I.H.P.,  each 

200  Ibs  

CONDENSERS  (A)  

Barometric  jet    

Two  for  one  engine. 
Vertical,  24  suction. 
Vertical,  steam  driven. 
Revolving  field. 

Circulating  pump 

Double  acting  compound     .    .    . 
Single  acting  

Air  pump        .    .            .        .    . 

GENERATOR  (A) 

5,000  K.W.,  each  ... 

Volt 

11,000  

Phase                   

•2      . 

Cycle  per  second 

2C 

Revolution  per  minute     .    .    . 
TURBO-GENERATOR  (B)  (3)    .    . 
Volt 

7c 

1,250  K.W.,  each  
1  1  ,000  .        

Two-stage  Westinghouse-Parsons. 

Phase                       

•2      . 

Cycle  per  second 

60          .                      

Lighting  exclusively. 

I  2OO 

CONDEVSERS     (B) 

4  500  sq.  ft.,  each          

Each  turbine,  one  apparatus. 
Vertical. 

Steam  driven, 
a            « 

Circulating  pump      

Double  acting  compound     .    .    . 
Two-stage   

Air  pump 

Hot  well  pumps 

Duplex     

EXCITERS  (2) 

vertical  cross  compound  .... 

Capacity                             . 

250  K.W.,  each      .    r   

Revolutions  per  minute   .    .    . 

I^O     . 

.   1 

1 

FIFTY-NINTH  STREET  PLANT,  NEW  YORK. 


407 


SUBJECT. 

REMARKS. 

CIRCULATING  WATER 
Volt 

2t;o 

Motor  generators  (3) 

250  K.W.,  each     

Storage  battery 

1  20  cells  

3,000  amp.  hour  at  one  hour. 
Six,  in  two  groups. 

AUXILIARIES,  electrical. 
Transformers,  total  

300  K.W  

Volts    

250  D.C.  and  400  A.C  

Storage  battery  

?<;  cells    . 

Operates  oil  switches. 

Six  hundred  3"  X  10"  bags,  each. 
25  Ibs.  pressure. 
Steam  driven. 

With  one  ro-ton  auxiliary  hoist. 
With  one  i5-ton  auxiliary  hoist. 
64'  7"  above  generator  floor. 

OILING  SYSTEM. 
Filtering  tanks  

2  at  6,500  gallons 

Elevated  supply  tanks      .... 
Pumps  (2)  ...        ..... 

2  at  3,500  gallons      

single  acting 

CRANES  (i)     

50  tons 

"       (0 

25  tons    

Span    

72'  o"  

408 


STEAM-ELECTRIC   POWER   PLANTS. 


LONG  ISLAND   CITY   PLANT. 


409 


FIG.  2.     Long  Island  City  Plant,  showing  Coal  Tower  in  Operation. 


FIG.  3.     Coal  Conveyor,  viewed  from  Tower,  Long  Island  City  Plant. 


STEAM-ELECTRIC  POWER   PLANTS. 

H    ^Q  S 


LONG  ISLAND  CITY  PLANT. 


411 


FIG.  5.     Interior  of  Generating  Room,  Long  Island  City  Plant,  5ooo-K.W.  Parsons  Turbines. 


FlG.  6.     Oil  Switch  and  Bus-Bar  Compartments,  Long  Island  City  Plant. 


412 


STEAM-ELECTRIC  POWER  PLANTS. 


T3 

C 
rt 


bJO 
O 


o 

0) 

CO 


LONG  ISLAND    CITY  PLANT. 


413 


FIG.  8.     Electrical  Operating  Gallery,   Long  Island  City  Plant. 


FIG.  9.     Bus  Gallery,  showing  Main  Generator  and  Rheostats  and  Auxiliary  Wiring 

Long  Island  City  Plant. 


414 


STEAM-ELECTRIC  POWER  PLANTS. 


FiG.  10.     Turbine  Room,  Basement,  Long  Island  City  Plant. 
(Showing  Condensers  and  Pumps.) 


LONG  ISLAND  CITY  PLANT. 


415 


€ 


rt 
S 


be 
C 

•c 


w 


CHELSEA,   LONDON. 


SUBJECT. 

REMARKS. 

BUILDINGS 

14  V  6"  X  17$'  o"  . 

143'  6"  X  100'  o"  

Coal  bunkers,  15,000  tons. 
Including  switch  room,  14'  o"  wide 
Three  storage. 
Accommodates  6  barges. 
Two  tiers. 

143'  6"  X     75'  o*  . 

OIL-COOLING  BUILDING 

50  ft.  high  

BARGE  BASIN 

220'  o"  X   80'  o"    

BOILERS,  accommodate  (80)     .    .    . 

B.  &  W       

64 

5  212  sq.  ft  

i7c  Ibs 

Stokers    chain-grate 

Si.  sq.  ft. 

Motor  driven. 

672  sq.  ft.    .             

Steam  pipe  connection      .... 
ECONOMIZERS  (20) 

6"      .                

14"  header. 
Two  tiers,  in  rear  of  boilers. 
Motor  cleaned. 

Green       

Heating  surface,  lotal    .        ... 

105,000  sq.  ft  

Heating  surface,  per  boiler  .    .    . 
CHIMNEYS                             .... 

1,640  sq    ft 

4   

Radial  brick. 
Natural  draft. 

Height  above  lower  grates   .    .    . 

2C?'  o" 

IQ'  o" 

COAL  HANDLING  system           .    .    . 

2  Gantrie  cranes    

Motor  driven. 

«            « 
Storage  battery  locomotive. 

C.  I.  and  W.  I. 

30"  belt            

"     (2)  . 

buckets    

"     (2) 

20"  belts      

\SH  HANDLING  system 

Industrial  railway      

CIRCULATING  WATER. 

5'  6"  diameter                 

Outlet 

5'  6"  diameter    

it        «         « 

8i"  artesian  well 

Pumps  (8)                                .    .    . 

vertical  plunger      

Steam  driven. 

TURBINES,  accommodate  (10)     .    . 
(i).    .    . 
"          at  present  installed  (8)    . 

5,000  K.W.  each    

British  Westinghouse-Parsons. 
it                   tt                   it 

2  700  K.\V  each    .        

5  ooo  K.W.  each    

16;  Ib 

Temperature,  superheat   .... 
CONDENSERS,  each    

15,000  sq.  ft  

27"    . 

Vertical,  surface. 
90  per  cent. 
Motor  driven. 

"Open"  type  . 

Circulating  pump               .... 

20"  

A" 

Dry  air    

GENERATOR                            

5,000  K.W  

Volt 

I  I  OOO                                               

Phase 

1 

111 

Revolution  per  minute      .... 

vertical  two-cylinder  compound    . 
150  K.W  

25  per  cent  overload  capacity. 

Revolutions  per  minute    .... 

Vnlt 

67~i    

AUXILIARIES,  electrical. 

125  K  W.                    

Charging  battery,  light,  etc. 

Volt 

T2C 

Operate  oil  switches. 
Three  groups. 

Motor  driven. 
Oil  is  cooled  then  filtered. 

Transformers,  total    

150  K.W.,  11,000  —  220  volts    . 
centrifugal       

OILING,  system. 

3,330  SQ.  ft.  each 

Total  capacity  per  min.        .    .    . 

BERLIN  PLANTS. 


417 


FIG.  i.     Light  and  Power  Plant,  "  Oberspree,"  Berlin. 


FIG.  2.     Interior  of  Engine  Room,  "Oberspree,"  Berlin. 


STEAM-ELECTRIC   POWER    PLANTS. 


FIG.  3.     Plan  of  "Oberspr^e"  Plant,  Berlin.     Coal  Handling  System  and  Storage  at  Right 
Hand  (Zeitschrift  des  Vereines  deutscher  fngenieure). 


BERLIN  PLANTS. 


419 


FIG.  4.     Light  and  Power  Plant,  "  Moabit  "  Plant,  Berlin. 


FIG.  5.     Interior  of  Engine  Room,  "Moabit  "  Plant,  Berlin. 


420 


STEAM-ELECTRIC   POWER   PLANTS. 


BERLIN  PLANTS. 


421 


g 

I 


5i 

« 


C/3 

hC 

C 

^ 

c 
rt 

w 

13 
o 
U 


422 


STEAM-ELECTRIC  POWER  PLANTS. 


FIG.  8.     Trebbiner  St.  Plant  of  the  Elevated  R.R.,  Berlin  (Power). 


ST.  DENIS,   PARIS. 


423 


SUBJECT. 

REMARKS. 

BUILDINGS. 
Boiler  rooms,  each     

140'  X  140'     

3  separate  buildings. 
Pumps,  purifier,  tanks,  etc. 
3  buildings. 
i  building, 
i  building. 
B.  &  W.  marine  type. 

Feed  water  rooms,  each   .    .    . 
Coal  and  ash  buildings,  each  . 
Generating  room        

140'  X     19'  6"        

140'  X  140'     

656'  X    65'  6"    

Switching  room 

620'  X      2?'       . 

BOILERS    number           

00              

At  present  installed  

20           

Under  construction    

20      

Size       .                

A   coo  SO.  ft. 

Each. 

Pressure  

175  Ibs.        .        •     

Superheat    

640  sq.  ft.    .        

Grate   

70  sq.  ft. 

Chain  grate. 
Motor  driven. 
Inter-connected,  8"  pipe. 
One  per  boiler. 
Motor  driven. 
One  for  10  boilers,  for  "make  up" 
water  only. 

Grate  operation      

10  H.P.  for  5  grates 

Pipe  connection      

5"  boiler,  12"  header 

ECONOMIZERS,  each  

1,720  sq.  ft.         

Scraper    .            

15  H.P.  for  5  economizers  .    .    . 
185  gal.  (U.S.),  145  gal.  (Brit.) 

4  per  20  boilers      ... 

WATER  PURIFIERS,  each  .... 
FEED  PUMPS  

"      (3)- 

triplex  acting  plunger            .    .    . 

80  H.P.  motor. 
100  H.P.  motor. 
One  for  5  boilers. 

"      (i)  

centrifugal 

CHIMNEYS  (12)      

radial  brick 

Height  above  grate    

i6<;'  o" 

Diameter  at  top     

10'  o" 

COAL  CONVEYOR  SYSTEM     .    .    . 
Coal-building  capacity      .    .    . 
Bunkers  

Two  40-50  ton  locomotive  cranes 
16,000  tons      

Motor  driven. 
Per  building. 
Per  2  boilers. 
For  coal  and  ashes. 

Concrete. 
ft 

Brown-Boveri-Parsons. 

80  tons 

Conveyor     

Bucket 

CIRCULATING  WATER    

2  intake  tunnels 

2  outlet  tunnels 

TURBINES   

12 

At  present  installed  

Under  construction    

A 

Capacity      
Steam  pressure  

5,000  K.W  

I7c  lb. 

Each. 

Steam  temperature    

S7o  °  Fahr 

Total. 

Revolutions  per  minute    .... 
CONDENSER  PLANT  

7<;o 

Surface 

Circulating  pump,  each    .... 
Air  pump  (wet)      

150  H.P.,  vertical  motor  .... 

Double  section,  centrifugal. 
Three-cylinder,  single  acting. 
Brown-Boveri. 
Fan  cooled. 

For  exciter,  motors,  etc. 

GENERATOR    

5  ooo  K  W 

Tvpes  

3-phase,  25-cycle,  10,250  volts    . 
2-phase,  42-cycle,  12,500  volts    . 

EXCITERS. 
Turbo-generator  (i).    ..... 

Condenser       

Surface    .                       .... 

Circulating  pump  
Air  pump  (wet)      

16.5  H.P.  motor     

o       H.P.  motor 

Motor  generators  (2)     

IT\  K  W.  each 

3-phase,  25-cycle,  10,250  volts. 

Volt      

220   . 

AUXILIARIES,  electrical. 
Booster    

no  H.P.,  220  volt     

Storage  battery       .    .            . 

126  cells  

1,300  amp.  hour  per  hour. 
12,500  volts  and  10,250  volts. 
D.C.  550  volts. 

Polymorphic  set     

Two  750-K.W.  alternators  (1,500 
K.W.)  and  two  generators     .    . 

424 


STEAM-ELECTRIC  POWER  PLANTS. 


NEW  YORK  CENTRAL  PLANTS. 

10     . 


425 


426 


STEAM-ELECTRIC   POWER   PLANTS. 


k 

<U 

8 

"5 


rt 

u 

•Sl 

O 
X 


C/5 


O 

5* 


I 

o 

;* 


in 


U 


NEW  YORK  CENTRAL  PLANTS. 


427 


o 

3-, 


•«*• 

6 


428 


STEAM-ELECTRIC   POWER   PLANTS. 


FIG.  5.     Interior  of  Boiler  Room,  "  Port  Morris  "  Plant,  New  York. 


NEW  YORK  CENTRAL  PLANTS. 


429 


g 

5 

be 


430 


STEAM-ELECTRIC  POWER  PLANTS. 


o 

AH 

bJO 

c 

'a 

PH 

S 
rt 


c 

'ct 
S 


NEW  YORK  CENTRAL  PLANTS. 


431 


If 


•a 
sS 


J8 
I 


.&• 

<u 

>-H 

<u 

I 

00 

d 


432 


STEAM-ELECTRIC   POWER   PLANTS. 


FIG.  9.     Remote-Control  Switchboard  '«  Port  Morris  "  Plant,  New  York. 


D.  &  H.   CO.,  MECHANICVILLE,  N.Y. 


433 


SUBJECT. 

REMARKS. 

BUILDING 

i6<;'  X  iss'     . 

165'  X    81'     

i6<;'  X    =54'     . 

Including  switch  room,  20'  wide. 

BOILFRS   (l6)                                    .... 

Stirling    

At  present  installed  (8)     .... 
Size   each 

Stirling    

4,350  sq.  ft.     

Pressure                            

17?  Ib. 

Superheater     

100°  Fahr  

Grate  (chain) 

145  sq.  ft.        

Extended  furnace. 
5"  auxiliary  header. 
Open  type. 
Duplex  plunger. 
Future. 
Duplex  piston. 
100  tons  per  hour. 
Motor  driven. 
Reinforced  concrete. 
Trolley  locomotive. 
Large  sunk  ash  pit. 

STEAM  PIPING            .        

6",  10"  header    

FEED-WATER  HEATERS  (2)  .    .    .    . 
FEED  PUMPS  (2)                           .    . 

5,000  H.P.  each     

14"  X  9"  X  12"      . 

d)     . 

14"  X  9"  X  12"      

HOUSE  PUMPS  (2)       

8"  X  ioj"  X  10"    .    .    . 

COAL  HANDLING    

Gantrie  crane,  2-ton  bucket     .    . 

i  ?o'  o" 

Span     

COAL  BINS  (16)         

1.2  tons  per  lineal  ft  
Narrow-gauge  railway  

Conveyor     

ASH  HANDLING                      .  '.    .    . 

Standard  and  narrow-gauge  ry.    . 
radial  brick,        

CHIMNEYS  (2)     

Height  above  grate    

83'  6"  . 

Forced  draft. 

Diameter  at  top     

9'  o"  

BLOWERS     

i  per  4  boilers    

Engine,  9"  X  10" 

CIRCULATING  WATER. 
Intake              .        

^'N     SQ.    ft. 

Concrete. 

G.  E.  Co.,  Curtis,  4  stage. 
Future. 

Outlet       

3s  sq.  ft. 

TURBO-GENERATORS  (2)  
TURBO-GENERATORS  (3)  

2,000  K.W.  each    

3,000  K.W.  each 

Phase   

3        

Cycle    

40     

Volt      

2,300    

Speed  

800  revolutions  per  minute  .    .    . 

CONDENSERS       

30"  elevated  jet  

1  6"  tail  pipe. 
Steam  driven,  horizontal. 
Rotative,  single  stage. 
Two-stage,  horizontal,  Curtis. 

Circulating  pump  

14"  centrifugal 

Dry  vacuum  pump    

10"  X  21"  X  12"    . 

EXCITERS  (2)  

75  K.W.  turbo-generators    .    .    . 
2,400  revolutions  per  minute   .    . 

Speed  

OIL  PUMPS  (2)    

•jy  x  2f"  X  10" 

20  gallons  per  minute  each. 

Pressure  

600  Ib  

Oil  tank   

i  filtering  tank  (i  future)     .    .    . 
30  tons     .... 

600  gallons  per  hour. 
54'  3"  above  generator  floor. 

CRANE     

Span     

52'  o"  

434 


STEAM-ELECTRIC  POWER  PLANTS. 


I 
ft; 


C 

oJ 

Pk 

•M 

CO 

<u 

a 

o 

S 

a 

o 


o 

i-, 

U 


COMMERCE  STREET  PLANT,  MILWAUKEE. 


435 


Plan  of  Commerce  St.  Plant,  Milwaukee  (Street  Railway  Jour naT). 


436 


STEAM-ELECTRIC  POWER  PLANTS. 


BOILER    HEATING    SURFACE    PER    K.W.    CAPACITY,   NORMAL  RATING,   OF    VARIOUS 
AMERICAN  AND  EUROPEAN  PLANTS. 


NAME  OF  PLANT. 

Square  Feet 
Heating 
Surface 
per  K.W. 

Type  of 
Prime 
Mover. 

Service. 

St.  Denis,  Paris     

4.r 

Turbines 

Subway  and  lighting 

Chelsea,  London  

7  6 

Long  Island  Citv  

7-6 

a 

Waterside    I,  New  York     .... 

6  ; 

H 

Waterside  II,           "              

80 

„ 

Power  and  lighting 

'Port  Morris,             "              

?.o 

« 

Heavy  railroading 

Yonkers,                   "              

s  O 

a 

5gth  Street,              "              

7  ? 

Engines 

Subway  railway 

74th  Street,              "              

8.2 

Elevated  railway 

96th  Street,              "              

6.7 

« 

Street  railway. 

Kingsbridge,            "              

c.6 

u 

Street  railway 

L  Street,  Boston    

8.2 

Turbines 

Power  and  lighting 

Potomac,  Washington      .... 

C    T 

Street  railway  and  lighting 

D.  and  H.,  Mechanicville,  New  York  . 
Bow  Road,  London      

6.9 

r.4 

Engines 

Slivct   railway  and  power. 
Power  and  lighting 

Municipal,  Vienna    .... 

60 

Power  and  lighting 

Delaware  Avenue,  Philadelphia  .... 

IO.O 

Turbines 

Street  railway. 

COMPARISON   OF    AREA    AND    VOLUME    OF    VARIOUS    AMERICAN    AND    EUROPEAN 
POWER   HOUSES,   PER   K.W.   CAPACITY. 


NAME  OF  PLANT. 

Square  Feet 
per  K.W. 

Cubic  Feet 
per  K.W. 

Number  of 
Boiler  Floors. 

Type  of  Prime  Mover. 

St.  Denis,  Paris    

2  08 

I 

Turbines  horizontal. 

Chelsea,  London  

i.ei 

142 

2 

Long  Island  City 

i.«6 

1  2O 

2 

«                  « 

Waterside    I,  New  York    .    .    . 

•95 

1  10 

2 

"          and  engines,  vertical. 

Waterside  II,          "              ... 

0.80 

108 

2 

"         vertical  and  horizontal. 

Port  Morris,            "              ... 

1.32 

IO2 

2 

"          vertical. 

Yonkers,                                 .    .    . 

1.32 

102 

2 

"               " 

59th  Street,             "              ... 

2.32 

259 

2 

Engines,         " 

74th  Street,             "             ... 

2.05 

222 

2 

"               " 

g6th  Street,                           .    .    . 

1.40 

170 

3 

«               « 

Kingsbridge,                          .    .    . 
L  Street,  Boston       

1.88 

2.4.C 

156 
148 

2 
I 

«               it 
Turbines,       " 

Fisk  Street,  Chicago    

2.42 

I4O 

I 

«              « 

Potomac,  Washington     .... 

i-SS 

84 

I 

«              « 

D.  and  H.,  Mechanicville,  N.Y. 
Bow  Road,  London     

2.22 
2.  QI 

130 
232 

I 

I 

tt              « 

Engines,         "       and  horizontal. 

L.:JJ 


; 


Plan  and  Cross-Section  of  Quincy  Plant  of  the  Massat 


aaisog  WMlf/OD  MOt^*-J5  «»ff 

\  -rWifr   .?      ' — 


tchusetts  Electric  Companies  (Street  Railway  Review} . 


APPENDIX. 


METRIC  SYSTEM  OF  WEIGHTS  AND  MEASURES, 

The  metric  system  is  based  upon  the. distance  from  the  equator  to  the  pole. 
Very  approximately  the  ten  millionth  part  of  this  arc  was  chosen  as  the  unit  of 
.measures  of.  length,  and  called  a  metre.  The  cube  of  the  tenth  part  of  the  metre  was 
adopted  as  the  unit  of  capacity,  and  denominated  a  litre.  The  weight  of  a  litre  of 
distilled  water  at  its  greatest  density  was  called  a  kilogram  of  which  the  thousandth 
part,  or  gram,  was  adopted  as  a  unit  of, weight.  The  multiples  of  t*hese,  proceed- 
ing in  decimal  progression,  are  distinguished  by  the  employment  of  the  prefixes  deca, 
hecto,  kilo  and  myria  (from  the  Greek),  and  the  subdivision  by  deci,  centiand  milli 
(from  the  Latin). 


METRIC  MEASURES. 


ENGLISH  EQUIVALENTS' 


LENGTH 

Single  Units. 

Meters. 

Inches. 

Feet. 

Yards. 

Miles. 

Millimeter.  .(mm.)~ 

001 

.03937 

.  00328 

Centimeter,  .{cm.)  — 

01 

.39371 

.03281 

.01094 

Decimeter,  .(dm.)— 

.1 

3.93708 

.32809 

.  10936 

Meter  ^  .  ..(M.)  — 

1. 

39.37079 

3.28090 

1  .  09363 

.00062 

Decameter.  (Dm.)  — 

10. 

32.80899 

10.93633 

.0062] 

Hectometer(Hm  )  — 

100. 

328  .  0899 

109.3633 

.06214 

Kilometer.  {Km.)  — 

1  000. 

3280.899 

1093.633 

.62138 

Myriameter(Mm  )— 

10  000 

6.21382 

SURFACE 

Single  Units. 

Sq.  Meters. 

Sq.  Inches. 

Sq.  Feet. 

Sq.  Yards. 

Sq:  Miles.' 

Sq.  Centimeter.  .  .  — 

.0001 

.155 

Sq   Decimeter....  — 

.01 

15.501 

.108 

Ca            (  —  Sq  m  )  — 

1 

1  550.059 

10.764 

1.196 

Are      "(—  Sq  Dm  )  — 

100. 

155  005.9 

1076.43 

119.603 

Hectare"1-  (SqHm  )— 

10000. 

107643. 

11960.33 

Sq  ICilometer  '       — 

1  000  000 

38613 

VOLUME 

Single  Units. 

Cu.  Inches. 

Cu.  Feet. 

Cu.  Yards. 

Liters. 

U.S.  Gals. 

Cubic  cm.   (  —  ml.)  — 

.0610 

.001 

.00026 

Cubic  dm.  (  =  liter)  = 
Cubic  met.  (=K1.)  = 

61.0271 
61027.06 

.03532 
35.3166 

.00131 
1.30802 

1. 
1000. 

.25418 
264.179 

WEIGHT 

Single  Units. 

Grams. 

Oz.  Avoir. 

Lb.  Avoir. 

2000  Ib.  T. 
(Net  Tons). 

TroyGr. 

Milligram  •  .  = 

.001 

.0154 

Gram  = 

1. 

.03527 

.00221 

15.4324 

Kilogram  — 

11  000. 

35.27394 

2.20462 

.001102 

Tonne  —  984  g  T  .  — 

1  000000. 

2204.6215 

1.102311 

1  gross  T.=  2240  Ib. 

437 


438 


APPENDIX. 


TABLE   OF   GALLONS   EQUIVALENT   TO   LITERS. 
(U.S.  GALLONS  OF  8.33  LB.) 


No. 

Liters  to 
Gallons  Liquid. 

Gallons  to 
Liters  Liquid. 

Cubic  Meters  to 
Gallons  Liquid. 

Gallons  to 
Cubic  Meters  Liquid. 

I 

0.2642 

3-7854 

264.17 

0.0038 

2 

0.5284 

7-5707 

528.34 

0.0076 

3 

0.7925 

II-356I 

792-51 

0.0114 

4 

1.0567 

IS-^IS 

1056.68 

0.0151 

5 

1.3209 

18.9268 

1320.85 

0.0189 

6 

I-585I 

22.7122 

1585.02 

0.0227 

7 

1.8492 

26.4976 

1849.19 

0.0265 

8 

2.1134 

30.2830 

2113.36 

0.0303 

9 

2.3776 

34.0683 

2377-53 

0.0341 

TABLE  OF  POUNDS  PER  CUBIC  AND  SQUARE  EQUIVALENT  TO  KILOGRAMS  PER  CUBIC 

AND    SQUARE 


No. 

Kilograms 
per  Cubic  Meter 
to  Pounds 
per  Cubic  Foot. 

Pounds 
per  Cubic  Foot 
to  Kilograms 
per  Cubic  Meter. 

Kilograms 
per  Square  Centimeter 
to  Pounds 
per  Square  Inch. 

Pounds 
per  Square  Inch 
to  Kilograms 
per  Square  Centimeter. 

I 

0.0624 

16.0192 

14.2232 

0.0703 

2 

0.1248 

32-0385 

28.4465 

0.1406 

3 

0.1873 

48.0577 

42.6697 

0.2109 

4 

0.2497 

64.0769 

56.8929 

0.2812 

5 

0.3121 

80.0962 

71.1161 

0.3515 

6 

0-3745 

96.1154 

85-3394 

0.4218 

7 

0.4370 

112.1346 

99.5626 

0.4922 

8 

0.4994 

128.1539 

113.7858 

0-5625 

9 

0.5618 

144.1731 

128.0090 

0.6328 

TABLE   OF  CUBIC  METERS  AND  CUBIC  CENTIMETERS  EQUIVALENT  TO  CUBIC  FEET 

AND    CUBIC   INCHES. 


No. 

Cubic 
Centimeters 
to  Cubic  Inches. 

Cubic  Inches 
to  Cubic 
Centimeters. 

Cubic 
Meters  to 
Cubic  Feet. 

Cubic 
Feet  to 
Cubic  Meters. 

Cubic 
Meters  to 
Cubic  Yards. 

Cubic 
Yards  to 
Cubic  Meters. 

I 

0.061 

16.3934 

35-3I6 

0.0283 

1.308 

0.7645 

2 

O.I22 

32.7869 

70.632 

0.0566 

2.616 

1.5291 

3 

0.183 

49.1803 

105.948 

0.0849 

3-924 

2.2936 

4 

0.244 

65-5738 

141.264 

0-II33 

5-232 

3.0581 

5 

0.305 

81.9672 

176.580 

0.1416 

6.540 

3.8226 

6 

0.366 

98.3607 

211.896 

0.1699 

7.848 

4.5872 

7 

0.427 

114.7541 

247.212 

0.1982 

9.156 

5-35I7 

8 

0.488 

I3I-I475 

282.528 

0.2265 

10.464 

6.1162 

9 

0-549 

147.5410 

317.844 

0.2548 

11.772 

6.8807 

APPENDIX. 


439 


KILOGRAMS  PER  METER  AND  SQUARE  METER  EQUIVALENT  TO  POUNDS  PER  FOOT 

AND   SQUARE   FOOT. 


No. 

Kilograms 
per  Meter 
to  Pounds 
per  Foot. 

Pounds 
per  Foot 
to  Kilograms 
per  Meter. 

Kilograms 
per  Square  Meter 
to  Pounds 
per  Square  Foot 

Pounds 
per  Square  Foot 
to  Kilograms 
per  Square  Meter. 

I 

0.6720 

1.4882 

0.2048 

4.8825 

2 

1-3439 

2.9764 

0.4096 

9.7649 

3 

2.0159 

4.4645 

0.6144 

14.6474 

4 

2.6879 

5-9527 

0.8193 

19.5299 

5 

3-3S98 

7.4409 

1.0241 

24.4123 

6 

4.0318 

8.9291 

1.2289 

29.2948 

7 

4-7^37 

10.4172 

1-4337 

34-1773 

8 

5-3757 

11.9054 

1-6385 

39-0597 

9 

6.0477 

I3-3936 

I-8433 

43.9422 

FOOT  HORSE-POWER  EQUIVALENT  TO  METRIC  HORSE-POWER  AND  TON  MEASURES. 


No. 

Horse-Power 
Metric  to  U.S. 

Horse-Power 
U.S.  to  Metric. 

Foot  -Pounds  to 
Kilogrammeters. 

Kilogrammeters 
to  Foot  -Pounds. 

Gross  Tons  per 
Square  Foot  to 
Metric  Tons 

Metric  Tons  per 
Square  Meter  to 
Gross  Tons 

per  Square  Meter. 

per  Square  Foot. 

I 

0.986 

1.014 

0-1383 

7.2329 

10-937 

0.091 

2 

1-973 

2.028 

0.2765 

14.4659 

21.873 

0.183 

3 

2-959 

3.042 

0.4148 

21.6988 

32.810 

0.274 

4 

3-945 

4.056 

0-5530 

28.9317 

43-747 

0.366 

5 

4-932 

5.069 

0.6913 

36.1646 

54.684 

o-457 

6 

5.918 

6.083 

0.8295 

43-3976 

65.620 

0-549 

7 

6.904 

7.097 

0.9678 

50.6305 

76.557 

0.640 

8 

7.890 

8.IH 

1.1061 

57.8634 

87.494 

o-73i 

9 

8.877 

9.125 

1.2443 

65.0963 

98.431 

0.823 

440 


APPENDIX. 


SPECIFIC   GRAVITIES  AND   WEIGHTS   OF  VARIOUS  SUBSTANCES. 


BASED  ON  PURE  WATER  AT  62°    FAHR.,  BAROMETER  30". 
WEIGHT  OF  ONE  CUBIC  FOOT,  62.355. 

Average 
Specific 
Gravity 
Water  =  i. 

Average 
Weight  of 
One  Cu.  Ft. 
Pounds. 

Air  at  60  degrees  Fahr.  atmospheric  pressure  (14.7  Ibs.  per  sq.  in.)  weights 

.00123 

1.4 
8.1 
8.4 

2.69 

2.72 

7-15 
7.69 

-77 
•55 
i-iS 

2.8 

7-85 
i 
i 

.0765 

35  to  45 
87 
5°5 
524 
i25 
15° 
52  to    60 
79  to    84 
47  to    52 
23  to    32 

135    tO   145 

80 
72  to     90 
90  to  i  10 
1  68 
170 
446 
480 
48 

34-3 
71.7 
90  to  106 
J51 
5  to     la 
175 
490 

62-35 
62-35 

Coke                                                

pitch                                     

Slate                                         

Steel                                  

Tar                                   

APPENDIX. 


441 


TABLE  OF  INCHES  AND  FEET  EQUIVALENT  TO  MILLIMETERS  AND  METERS. 


No. 

64ths  of  an  Inch 
to 
Millimeters. 

Millimeters 
to 
64ths  of  an  Inch. 

Inches 
to 
Centimeters. 

Centimeters 
to 
Inches. 

Meters 
to 
Feet. 

Feet 
to 
Meters. 

I 

0.3969 

2-5I97 

2-54 

0-3937 

3.2808 

0.3048 

2 

0.7938 

5-°394 

5.08 

0.7874 

6.5617 

0.6096 

3 

1.1906 

7-5590 

7.62 

1.1811 

9.8425 

0.9144 

4 

I-5857 

10.0787 

10.16 

I-5748 

i3-I233 

1.2192 

5 

1.9844 

12.5984 

12.70 

1.9685 

16.4042 

1.5240 

6 

2-3813 

15.1181 

i5-24 

2.3622 

19.6850 

1.8288 

7 

2.7781 

17.6378 

17.78 

2-7559 

22.9658 

2.1336 

8 

3-I750 

20.1574 

20.32 

3.1496 

26.2467 

2.4384 

9 

3-57J9 

22.6771 

22.86 

3-5433 

29-5275 

2.7432 

TABLE  OF  SQUARE  INCHES  AND  SQUARE  FEET  EQUIVALENT  OF  SQUARE  CENTI- 

•METERS  AND  SQUARE  METERS. 


No. 

Square  Inches 
to  Square 
Centimeters  . 

Square 
Centimeters  to 
Square  Inches. 

Square  Feet 
to 
Square  Meters. 

Square  Meters 
to 
Square  Feet. 

Square  Yards 
to 
Square  Meters. 

Square  Meters 
to 
Square  Yards 

I 

6.4516 

0.155 

0.0929 

10.7639 

0.8361 

1.196 

2 

12.9032 

0.310 

0.1858 

21.5278 

1.6722 

2.392 

3 

I9-3548 

0.465 

0.2787 

32.2917 

2.5084 

3-588 

4 

25.8064 

0.620 

0.3716 

43-0556 

3-3445 

4.784 

5 

32.2581 

0-775 

0.4645 

53-8I94 

4.1806 

5.980 

6 

38.7097 

0.930 

0-5574 

64.5833 

5.0167 

7.176 

7 

45-l6l3 

1.085 

0.6503 

75-3472 

5-8528 

8-372 

8 

51.6129 

1.240 

0.7432 

86.IIH 

6.6890 

9-568 

9 

58.0645 

1-395 

0.8361 

96.8750 

7-5251 

10.764 

TABLE  OF  POUNDS  AND  NET  TONS  EQUIVALENT  TO  KILOGRAMS  AND  METRIC  TONS 


No. 

Avoirdupois 
Pounds  to 
Kilograms. 

Kilograms 
to  Pounds 
Avoirdupois. 

Net  Tons 
to 
Metric  Tons. 

Metric  Tons 
to 
Net  Tons. 

Gross  Tons 
to 
Metric  Tons. 

Metric  Tons 
to 
Gross  Tons. 

i 

0.4536 

2.2046 

0.9072 

1.1023 

1.0161 

0.9842 

2 

0.9072 

4.4092 

1.8144 

2.2046 

2.0321 

1.9684 

3 

1.3608 

6.6138 

2.7216 

3.3069 

3.0482 

2.9526 

4 

1.8144 

8.8184 

3.6288 

4.4092 

4.0642 

3.9368 

5 

2.2680 

11.0230 

4.5360 

5-5II5 

5.0803 

4.9210 

6 

2.7216 

13.2276 

5-4432 

6.6138 

6.0963 

5-9052 

7 

3-I752 

15.4322 

6.3504 

7.7161 

7.1124 

6.8894 

8 

3.6288 

17.6368 

7.2576 

8.8184 

8.1285 

7-8736 

9 

4.0824 

19.8414 

8.1647 

9-9207 

9-M45 

8.8578 

442 


rks 


do 


o 


o  o 

«  ^, 

2  /•• 

£  sj  o 

.s5  g    « 

?  |   « 


*8 


0    d 


000 


CO 


r^ 

oo 

CO 
COiO<N 

1— I  »H  IO 

OCO»O 

'06^' 

<MCO 


osooo     co 

(N'-'CO^'^ 
OOCOCO^OCO 


g  :«E 

•:  •  fc 

^  'Sri 

-<J  '"3 

OCO 


CO 


'-8 

O 


<N 

CO     -OOQ 


U3 

•(-> 


O 

'•6 


l>. 

00 
CO 


C5  00  CD  CO  CO 
(M^CO'*'* 

00  CO  CD  ^O  CO 


CO 
OrHlOOO 


CD 

CO      t^OO1^ 
0 1--  »C  <>-(  T}< 

cooicoio 


i-iOO 
00 
OO 


oo-tf 


CO'* 


r-C*00»O 
CO 


0 

<u 
Pn 


o 


00 
lO 


1-4!^. 

<N 


Tft^iO  ^4O5CO'-i»O 

COCOO  O500iO'-irt4 

COCOCO  i-tCOiOi-4-^ 

OI-HTH  OO'-iCOOl 


lO      Tt400^00 
CO       <N<N 


w 

<u 
^3 

| 

O 

is 

p 
o 


CO 


i-iOOCO      t>-OOt^i-H>      COt^OOt^O 
COCOOCOiO 


ooioooo 

100' 
(MCO 


r-ICO 


<O<N 
O 


CO 


«    *20  w  o 


APPENDIX. 


443 


w 

3 

£-1 


EASURES.—  LENGTH 
LENGTH. 


TS  OF  WEIGHTS 


IOOO3CO 
OC<IO»O 
OOCOOO. 


oo 

OOi-<O 
OOOO 
OOOO 


•<NOrH 

•OCOOJ 


(N 

OJ 
(Ni-iTt<rt< 


IOO 


Tf<rH 

iCO 

(NOO 


(NOO. 

OSCO 


(MOrH 
C00> 


(N 


TflrH 

lO  0  1-4 
(MOO 
Or»<OOTl< 


coo 


OJ 


o 

lO 


>H  O 


CO 

rH»O 

CO<N 


IO 

rH 

»O 


CO 
O 
O 
O 

O 

O 


OCOOO 

lOOrH 

8COOO 
OrH 


Oi 


O 

IO 


OrHOSOO' 

OOO5CO 
OOrHOO 


tHTj<OOO 

<NCO 

COCO 


00 

Oi 


OOCO 
I>CO 
(N  CO, 

OCO 


rHOi 


U3  IN. 

IO<NO*CD 


O  rH  O5  rH 

OOOCO 


rHCM 


rHCO 
OJ 
0 


CO 


CO       CO 
<NOOOO 


OCOOOCO 
OO<NOO 


rHCO 


COCOOO 

rHCOOOOO 
(NO 
»OCO 


COO 
00 
<N 
CO 


i— 

8 


THCNcO 
rHCO 


OOINO 

OJOJCO 


CO 
CO 


OJCOO 
COOJl^ 

oco  co 

*OJ 
CO 


^'o'H 

!  o  g  *3 


s     eta 


SURFACE 


cr 

CO 


D1 
CO 


fi 
.  O 

cr 

CO 


CO 


«H 

9 

>*' 

61 

CO 


CO 


cr 

CO 


.    Oi 

coos     cooiros 

O<N       CXXN^.OS 

oo 


•  o 
•o 

:8 


iO(NTt* 
CO  OCO 

OTtJO 

OCO-OJ 


CO 


O) 


CD 
CO 
00 


coioco 


1HO 

o 
o 


THOO 

oo 


o 
o 
o 


OJ  co< 

<N  CO' 

(N  O' 

O  <N 

O  O 

(^  ^5 

CD  ^D 


<N 


O 


N.I-I 


OrH 
OrH 


<N 


CO 


988 


(NO 

OrH 

O 


co    • 

05 


TH      • 

O5rH 


°° 
OcO 


OO 


CO 
00 


888 


CJO-tf 
<N(NCD 


CO 


O      O 


82 


' 


444 


APPENDIX. 


Remarks 


same  as 
LTroy. 


o 
u 


m 
unce 


.OS 

0=2, 


^   0) 

o  t>c 


gra 

dra 
1  o 


a 

bo  <4_,  > 
M<  O  oJ 
coo 


Pound,  ounce  and 


45  drops  =  1  fluid 
2  tablespoonfuls  = 


wo 


0-9 

•P  52 


M 


w 

a 
g 

o 


no 


T*<  CO  00  TT» 

coos 55  o- . 

O  <N  CO  r-t  « 

'  TH  CO'  TH  CO 

CO  t- 


11 


r-l  (MO 

THN 

Ol 


w    . 

0)    U 

GO 


T-l  CO 


_>QQ 

:  O  CD  Is-  i 
">O>i 


>  •<*  CO  <_      _ 
>O  TH  O  TH 

'THCO' 


g 


m 
ce 
nd 
t. 
on 


d 
Boun 
poun 
cw 


ra 


grain 
ruple 
dram 
unce 
ound 


p 


UNITS 


dry  and  shaken 
dry,  average 
acite  coal,  loose 
inous  "  " 
hite  or 


Norway 


ms 
ounces 
pounds 
cwt. 


16 
16 

12 
20 


dra 


G    -  o 

*!2  •*->  G 

2   ^  § 

WO  O 


s 
les 
s 


heat 
ats 
nd, 
y 


hr 
m 
w 


a 
n 
itu 
e, 


s 


w 
o 
a 
cl 
a 
b 
in 


20  grain 
3  scrup 
8  dram 
12  ounce 


APPENDIX. 


445 


QQ 


• 


00 
H 


446 

APPENDIX. 

fri     0 

w 

•^f           •  C5 

§0     S» 

II'S 

O          -0 

^  o  cq    •  o 

^       0 

o      o1 

T«         r^      •         rH 

^  .          C/3 

rH        rH      • 

M                                                         •+» 
<1)                                                                 r-*     • 

•I                                                     ,1        ^'§ 

w 

T—  1 

0       0 

• 

•f_j      W  w 

w                                                         •  * 

G  ^'«« 

<N       O 

QQ 

^  Pi  n< 

CO         CO         rH  Tf< 

{D 

fefN              ,                              ft'      St 

(K      w 

iH        O               rH 

o 

<••»   II                                                       ll>        -t-1 
§  "                                             -g       oJnd- 

s 

OX            2                               f>       £  C 

g 

<N 

* 

w 

•  r-t 

°     '             rt                                <«*-»       'n  -^ 

CO4""                   O                                                ;                        Oj 

|l 

0 

ooo 

(^ 

I-- 

o 

*o 

i—  1  1^*                                         '•*-*                 JH          C      • 

^^        S           §       '5    '§"? 
II  II       -S                   P*    ft^ 

Cj                       ^™»                                .     ^* 

'rt  D* 

\-t    W 

CO     *O     '     'd 
CO       O             l> 
0      0 

G 

r-l        rH 

HH 

o 

*tH 

OPn             bo               *O             G        G*o 

a 

Co 

O    O                  Q                       -j               r-l        rH 

•HIH       CM           o       -g  .-g  g 

Q^ 

•                              ^"1                             fn                     ^    ^  ^    f^    ^J 

w 

« 

&«3 

••a 
PI 

CJ 

bp             43 

s»"        •§          •-       5^-S-^ 
^             g            »d             P     S 

00 

00 

rH             'Tj^CO 

coo       -oo 

COO          -O  b>« 

oo       -oo 

CO 

1 

g"         ^           Si       "S'S'S  °. 

|x    ^       S     8:*8I 

g       S 

rH        rH      • 

1 

lHrH               r^                    °               f5*O   S  ** 

jo  »            ...  c^                      c  92  P  ^j 

«) 

a  .,  . 

pZti 

fco^-S 

O  OJ   5 

r3&a 

00 
00 

O  rH  O         Tj<  CO 

CO       O            O 
CO      O           t>. 

0      0 

<J 

Qy     (1                                                  rH     CL          ^^ 
TT~j                                   t"^j  O                           0^  ~r"^      ^  O 

M 

rH        i-H 

V                      ^'S                 C                "^    g  **cn 

CQ 

*3-             c3rd                      -S  "^-S 

w 

O                          "^    n^                                       0      •    O      • 

t-i                   oi          •  t~<           55  f_^  ^f_5 

<!>  oi 

o  <u 

Oi         •  b- 

s 

-^       ^co     §     TO  -c0 

o  oo   •  o  oo 

O  CO     •  O  CO 
OOJ     -OO 

C3 
f^» 

ffi                     rJO               HH                  H          H 

ft 

M 

II  !!         II  II          ii          11      H 

11  il  II  II  II  II 

<•       . 

03 

4* 

•  S 

H 

.ft                      ^^^ 

V   G 

6  °     +> 

\~ 

H^                        'O                                     r;^         '(£ 

R  CJ       o 

pj 

to 

§•3           S                 |    -g 

&    St-'.S 

[^ 

.•a 

l-t  *      ^     *l 

a 

G  §        ^fe         !       -^    S 
H  «                   -S       o    «5 

(j)  0)         j4,  M 

£i,rJM              o  <D              n            ,^       r 
C-H              P,<^>          '<£        R'O       HH 
*                           VH          5*                 ^> 

II  £s,= 

0,3               <D  oJ         Q   <U         *-  <U         <^ 

•g|       ?3o    II    |g    | 

to1 

o  'bo-    d>  rj 

8-2     II- 

^J  T-l                   ?*>    O 

.OW     -^OW     'SO     ^Q     Q 

a 

<dM    Qo, 

B             **                          § 

S 

TH  ^  rH  rH  rH  rH 

^)  ^^  ^"^           *^^^™^                    **s  ^ 

in 

tcj         ^         Q      h. 

ft, 

APPENDIX. 


447 


(Kent.) 


DECIMALS  OF  A  FOOT,  EQUIVALENT 

TO  INCHES  AND  FRACTIONS  OF  AN  INCH. 


.Inches. 

0 

i 

i 

1 

* 

f 

5 

£ 

0 

0 

.01042 

.02083 

.03125 

.04167 

.05208 

.06250 

.07292 

1 

.0833 

.0938 

.1042 

.1146 

.1250 

.1354 

.1458 

.1563 

2 

.1667 

.1771 

.1875 

.1979 

.2083 

.2188 

.2292 

.2396 

3 

.2500 

.2604 

.2708 

.2813 

.2917 

.3021 

.3125 

.3229 

4 

.3333 

.3438 

.3542 

.3646 

.3750 

.5854 

.3958 

.4063 

5 

.4167 

.4271 

.4375 

.4479 

.4583 

.4688 

.4792 

.4896 

6 

.5000 

.5104 

.5208 

.5313 

.5417 

.5521 

.5625 

.5729 

7 

.5833 

.5938 

.6042 

.6146 

.6250 

.6354 

.6458 

.6563 

8 

.6667 

.6771 

.6875 

.6979 

.7083 

.7188 

.7292 

.7396 

9 

.7500 

.7604 

.7708 

.7813 

.7917 

.8021 

.8125 

.8229 

10 

.8333 

.8438 

.8542 

.8646 

.8750 

.8854 

.8958 

.9063 

11 

.9167 

.9271 

.9375 

.9479 

.9583 

.9688 

.9792 

.9896 

DECIMAL  INCHES  AND  MILLIMETERS 

EQUIVALENT  TO  FRACTIONS  OF  AN  INCH. 

Inches. 

Milli- 
meters. 

Inches. 

Milli- 
meters. 

Inches. 

Milli-  . 
meters. 

& 

.0156 

.397 

H 

.3438 

8.73 

H 

.6719 

17.07 

& 

.0313 

.79 

« 

.3594 

9.13 

11/16 

.6875 

17.47 

& 

.0469 

1.19 

3/8 

.3750 

9.53 

H 

.7031 

17.86 

1/16 

.0625 

1.59 

2R 
55 

.3906 

9.92 

as 

32 

.7188 

18.26 

& 

.0781 

1.98 

if 

.4063 

10.32 

47 
55 

,  .7344 

18.66 

& 

.0938 

2.38 

11 

.4219 

10.72 

3/4 

.7500 

19.05 

t 

5? 

'.1094 

2.78 

7/16 

.4375 

11.12 

49 

81 

.7656 

19.45 

1/8 

.1250 

3.18 

H 

.4531 

11.51 

§1! 
5 

.7813* 

19.85 

£ 

.1406 

3.57 

52 

.4688 

11.91 

8i 

.7969 

20.25 

p 

3! 

.1563 

3.97 

ii 

.4844 

12.31 

13/16 

.8125 

20.64 

ii 

.1719 

4.37 

1/2 

5000 

12.70 

P3 

55 

•  .8281 

21.04 

3/16 

.1875 

4.76 

II 

.5156 

13.10 

II 

.8438 

21.44 

il 

.2031 

5.16 

if 

.5313 

13.50 

M 

.8594 

21.83 

& 

.2188 

5.56 

11 

.5469 

13.89 

7/8 

.8750 

22.23 

IB 
B¥ 

.2344 

5.95 

9/16 

.5625 

14.29 

fir 

it 

-.8906 

22  63 

1/4 

.2500 

6.35 

II 

.5781 

14.69 

ii 

.9063 

23.02 

.     « 

32 

.2656 
.2813 

6.75 
7.15 

ii 

39 

55 

.5938 
.6094 

15.09 
15.48 

59 

5* 
15/16 

.9219 
.9375 

23.42 

23.82 

19 

SI 

.2969 

7.54 

5/8 

.6250 

15.88 

«i 

.9531 

24.22 

5/16 

.3125 

7.94 

ii 

.6406 

16.28 

ii 

.9688 

24.61 

ii 

.3281 

8.34 

ii 

.  6563 

16.67 

fi3 

BJ 

.  9844 

25.01 

1  in.  =  25.40  mm.  =  2.54  cm, 


INDEX. 


A. 

Ados  (Sarco)  CO2  Recorder,  116. 

Air  pump,  266. 

Air  required,  combustion,  113. 

Analysis  of  coal,  in. 

Anchors,  piping,  189. 

Appendix,  437. 

Architectural  features,  69. 

boiler  room,  80. 

crane,  76. 

chimneys,  83. 

conclusion,  83. 

doors,  76. 

floors,  76. 

galleries,  78. 

review,  69. 

switchboard,  80. 

walls,  78. 

windows,  76. 
Area  of  condenser  water  tunnels,  39. 

of  power  houses  per  K.W.  capacity, 

of  screens,  39. 

Ash  handling  system,  59th  Street  Plant, 
York,  351. 

St.  Denis  plant,  Paris,  340. 
Ashes,  removal,  82. 
Automatic  damper  regulator,  133. 
Auxiliaries,  steam  consumption  of,  263. 
Auxiliary  buildings,  26. 
Auxiliary  electrical  equipment,  Chelsea 
London,  370. 

St.  Denis  Plant,  Paris,  346. 

B. 

Baffle  wall,  chimneys,  146. 
Base,  column,  64. 
Battery,  storage,  290. 
Beams,  floor,  65. 
Bearing  power  of  soil,  44. 


436. 


New 


Plant, 


Bedplate,  grouting,  48. 

Blower,  steam,  130. 

Boiler,  Babcock  &  Wilcox,  93. 

blow-off  piping,  216. 

corrosion  of,  148. 

durability  of,  88. 

efficiency  of,  9. 

foreign  types,  99. 

grate  surface,  88. 

heating  surface  per  K.W.  capacity,  436. 
Boiler,  feed  piping,  215. 

pumps,   268. 
Boiler  feed  water,  148. 

impure,   148. 

mud,  149. 

plant,  59th  Street,  New  York,  355. 

plant,  St.  Denis,  Paris,  342. 

plant,  Twin  Municipal,  Vienna,  387. 

pure,   148. 

purifier,  150. 

scum,  150. 

storage,  154. 
Boiler  house,  17. 

architectural  features,  80. 
Boiler  room  equipment,  St.  Denis,  Paris,  341. 

Fisk  Street,  Chicago,  373. 

Twin  Municipal,  Vienna,  387. 

safety,  86. 

scale,  149. 

setting,  91. 

size,  92. 

Stirling,  95. 

simplicity,  88. 
Boiler  tests,  318. 

method  of,  319. 

trimmings,  92. 

types,  85. 

water  circulation,  88. 

Wickes,  97. 


449 


450 


INDEX. 


Building,  48. 

auxiliary,  26. 

doors,  53. 

elevators,  56. 

floors,  48. 

frame,  structural  steel,  61. 

heating,  58. 

lighting,  58. 

material,  48. 

plumbing,  56. 

stairways,  56. 

toilets,  56. 

ventilating  of,  53. 

walls,  52. 

windows,  52. 
Bunker  fires,  38. 
Bunker,  overhead,  36. 
Bus-bar  chambers,  285. 

C. 

CO_,   recorders,  115. 
Central  condenser,  252. 
Chain  grate  stoker,  102. 
Chelsea  Plant,  London,  361. 

auxiliary  electrical  equipment,  370. 

boilers,  365. 

chimneys,  366. 

circulating  water  supply,  361. 

coal  handling  system,  362. 

condenser  plant,  367. 

dimensions  and  data,  416. 

economizers,  365. 

exciters,  368. 

feed  water,  365. 

oil  cooling  system,  368. 

piping,  367- 
substructure,  361. 
superstructure,  362. 
switching  n-om,  369. 
turbo-generators,  366. 
wiring  system,  370. 
Chimneys,  83,  136. 
baffle  wall,  146. 
character  of,  136. 
Chelsea  Plant,  London,  366. 
draft,  121. 
guyed,  144. 


Chimneys  —  continued. 

ladders,  146. 

lightning  arresters,  147. 

lining  of,  145. 

Long  Island  City  Plant,  146. 

material  of,  136. 

radial  brick,  139. 

reinforced  concrete,  140. 

self  supporting,  145. 

steel,  142. 

Twin  Municipal  Plant,  Vienna,  392. 

59th  Street  Plant,  New  York,  139. 
Circulating  water,  piping,  220. 

pumps,  264. 

Chelsea  Plant,  London,  361. 

59th  Street  Plant,  New  York,  351. 

Twin  Municipal  Plant,  Vienna,  385. 
Closed  feed-water  heater,  156. 
Coal,  104. 

analysis,  in. 

character  of,  no. 

Coal  handling  system,  Chelsea  Plant,  London, 
362. 

59th  Street,  New  York,  351. 

St.  Denis,  Paris,  340. 

Twin  Municipal,  Vienna,  384. 
Coal,  heat  value  of,   105. 

piles,  exposed,  28. 

supply,  9. 
Coal  storage  plants,  26,  82. 

character  of,  30. 

comparison  of,  35. 

description  of,  30. 

Hamburg,  Germany,  34. 

Metropolitan  Co.,  London,  34. 

Shadyside,   New  York,  31. 

Twin  Municipal,  Vienna,  34,  384. 
Column  Base,  64. 

Columns,  Types,  Structural  steel,  62. 
Combustion,  113. 

air  required,  113. 

recorders,  CO2,  115. 

spontaneous,  29. 
Complete  unit  system,  17. 
Compound  engines,  227. 
Concrete  mat  construction,  42. 

forms,  47. 


INDEX. 


451 


Concrete  mat  construction  —  continued. 

mixture  of,  47. 

piles,  43. 
Condenser,  240. 

application  of,  244. 

central,   252. 

classification  of,  244. 

jet,  246. 

principle  of,  240. 

surface,  248. 
Condenser    plant,    Chelsea    Plant,    London, 

367- 

59th  Street,  New  York,  358. 

Fisk  Street,  Chicago,  377. 

St.  Denis,  Paris,  344. 

Twin  Municipal,  Vienna,  384. 
Condenser  water  required,  244. 

scarcity  of,  40. 

shut-off  gates,  39. 

supply  of,  38. 
Condenser  water  tunnels,  38. 

arrangement  of,  39. 
Cooling  ponds,  258. 

towers,  254. 
Corrosion,  boiler,  148. 
Cost  of  land,  n. 

of  power  plants,  4. 
Covering,  high-pressure  piping,  213. 

architectural  features  of,  76. 

low-pressure  piping,  221. 
Crane,  runway  of  structural  steel,  61. 

Twin  Municipal  Plant,  Vienna,  394. 

59th  Street  Plant,  New  York,  361. 

D. 

Dampers,  automatic  regulator,  133. 

of  smoke  flues,  133. 
D.   &  H.    Co.    Plant,  Mechanicville,  N.  Y., 

dimensions  and  data,  433. 
Design  of  small  plants,  22. 
Distribution,  current,  9. 
Doors,  53. 

architectural  features,  76. 

of  smoke  flues,  133. 
Draft,  119. 

chimney,  121. 


Draft  —  continued. 

meaning  of,  119. 

forced,  127. 

induced,  128. 

mechanical,  127. 

production  of,  120. 

loss  of,  120. 
Drip  piping,  210. 
Drips,  exhaust  piping,  220. 

E. 

Economizers,  157. 

Chelsea  Plant,  London,  365. 
Efficiency  of  boilers,  90. 

of  power  plants,  2. 
Electric  or  steam  driven  pumps,  262. 
Electrical  equipment,  274. 

Chelsea  Plant,  London,  370. 

Fisk  Street  Plant,  Chicago,  380. 

introductory,  274. 

59th  Street  Plant,  New  York,  359. 

St.  Denis  Plant,  Paris,  346. 
Elevators,  56. 
Employee's    advantages,    Fisk    Street    Plant, 

Chicago,  381. 
Engines,  comparison  with  turbines,  222. 

compound,  227. 

59th  Street  Plant,  New  York,  337. 

house,  21. 

quadruple  expansion,  230. 

tests  of,  325. 

triple  expansion,  229. 

Twin  Municipal  Plant,  Vienna,  392. 

simple,  226. 
Excavation,  41. 
Exciters,  278. 

Chelsea  Plant,  London,  368. 

Twin  Municipal  Plant,  Vienna,  394. 

59th  Street  Plant,  New  York,  359. 
Exhaust  piping,  drips  of,  220. 

fittings  of,  218. 

material  of,  218. 

size  of,  217. 

Expansion  of  pipes,  188. 
Expansion  joints,  smoke  flues,  132. 

structural  steel,  64. 
Extension,  space  for  future,  n. 


452 


INDEX. 


F. 
Feed-water  heaters,  154. 

closed  type,  156. 

economizer,  157. 

open  type,  154. 

percentage  of  gain,  160. 
Feed-water    plant,    St.    Denis    Plant,    Paris, 

342. 

Fiber  stresses  in  structural  steel,  64. 
Fifty-ninth  Street  Plant,  New  York,  349. 

boilers,  354. 

circulating  water  system,  351. 

coal  and  ash  handling  system,  351. 

condenser  plant,  358. 

cranes,  361. 

dimensions  and  data,  406. 

electrical  equipment,  359. 

feed- water  supply,  355. 

oiling  system,  361. 

prime  movers,  357. 

removal  of  gases,  354. 

steam  piping,  355. 

turbo-generators,  359. 
Filtering  tanks,  oil,  269. 
Fire,  bunker,  38. 

pumps,  268. 
Fisk  Street  Plant,  Chicago,  370. 

advantages  for  employees,  381. 

boiler  room  equipment,  373. 

building,  371. 

condenser  plant,  377. 

electrical  equipment,  380. 

oiling  system,  378. 

steam  piping,  374. 

switching  room,  380. 

turbo-generators,  374. 
Fittings  of  exhaust  piping,  218. 

of  high-pressure  piping,  195. 
Flanges,  pipe,  195. 
Floors,  48. 

architectural  features,  76. 
Floor  beams,  65. 
Floor  loads,  structural  steel,  63. 
Forced  draft,  127. 
Forms,  concrete,  47. 
Foundations,  41. 

location  of,  47. 


Foundations  — continued. 
size  of,  46. 
waterproofing  of,  48. 

G. 

Gallery,  switchboard,  52. 
Galleries,  architectural  features,  78. 
General  layout  of  power  plants,  12. 
Generators,  274. 

leads  of,  278. 

tests  of,  333. 

Twin  Municipal  Plant,  Vienna,  393. 

59th  Street  Plant,  New  York,  357. 
Grate  surface,  89. 
Grates,  99,  104. 
Grouting,  48. 
Guyed  chimneys,  144. 

H. 

Hangers,  pipe,  190. 
Heat  value  of  coal,  105. 
Heaters,  feed- water,  154. 
Heating,  building,  58. 
Heating  surface  of  boilers,  88. 
High-pressure  piping,  181. 
House  pumps,  266. 
Hot  well  piping,  220. 
Hot  well  pumps,  266. 

I. 

Impulse  turbines,  232. 
Inclined  grates,  102. 
Induced  draft,  128. 
Inspection,  structural  steel,  66. 
Insulation  of  steel  frame,  68. 


Jet  condenser,  246. 


J- 


L. 


Labor,  local  supply,  12. 

Ladders,  chimney,  146. 

Land,  cost,  n. 

Layout,  general,  of  power  plants,  12. 

Layout,  St.  Denis  Plant,  Paris,  336. 

Leakage  of  smoke  flues,  133. 

Lighting,  building,  58. 


INDEX. 


453 


Lightning  arresters,  chimney,  147. 
Lining  of  chimneys,  145. 
Local  labor  supply,  12. 
Location  of  foundation,  47. 

of  power  plants,  9. 
Low-pressure  piping,  217. 

covering,  221. 

M. 

Masonry,  weight,  46. 

Mat  construction,  concrete,  42. 

Material  of  buildings,  48. 

of  chimneys,  136. 

of  exhaust  piping,  218. 

of  high-pressure  piping,  195. 

of  superheaters,  163. 
Mechanical  draft,  127. 
Mechanical  stokers,  99. 

advantages  and  disadvantages,  99. 

chain  grates,  102. 

inclined  grates,  102. 

system  of,  101. 

underfeed,  102. 

O. 
Oil,  cooling  system,  Chelsea,  London,  368. 

filtering  tanks,  269. 

piping,  272. 

pumps,  268,  271. 

required,  268. 

supply  tanks,  271. 

switches,  285. 
Oiling  system,  268. 

Fisk  Street  Plant,  Chicago,  378. 

59th  Street  Plant,  New  York,  361. 
Open  feed-water  heater,  154. 
Operating  force,  St.  Denis  Plant,  Paris,  349. 
Overhead  Bunkers,  36. 

P. 

Painting,  structural  steel,  66. 
Piles,  concrete,  43. 

exposed  coal,  28. 

test  of,  44. 
Piping,  anchors,  189. 

boiler  blow-off,  216. 


Piping  —  continued. 

boiler  feed,  215. 

Chelsea  Plant,  London,  367. 

circulating  water,  220. 

covering,  213. 

drip,  210. 

expansion,  188. 

fittings,  195. 

flanges,  195. 

general  consideration,  182. 

hangers,  190. 

high-pressure,  181. 

hot  well,  220. 

low-pressure,  217. 

oil,  272. 

size  of  high-pressure,  181. 

size  of  exhaust  piping,  217. 

supports,  190. 

system  of  high-pressure,  183. 

trenches  for,  51,  78. 

vacuum,  220. 

valves,  206. 
Piping,  steam,  Fisk  Street,  Chicago,  374. 

59th  Street  Plant,  New  York,  355. 

Twin  Municipal  Plant,  Vienna,  392. 
Plants,  small,  boilers,  306. 

boiler  feed-water  supply,  307. 

coal  and  ash  handling  systems,  305. 

condensers,  312. 

conclusion,  316. 

design  of,  292. 

exciters  and  air  compressor,  313. 

flues  and  smokestack,  308. 

foundation,  296. 

location,  296. 

masonry,  300. 

sanitary  and  architectural  features,  302. 

steam  piping,  309. 

superstructure,  298. 

switchboard  and  wiring  system,  313. 

turbines  and  generator,  311. 

type  and  size,  294. 
Plumbing,  56. 
Potomac  Plant,  Washington,  D.C.,  dimensions 

and  data,  399. 
Power  plants,  cost  of,  4. 

efficiency  of,  2. 


454 


INDEX. 


Power  plants  —  continued. 

general  layout  of,  12. 

location  of,  9. 

practical  problems,  i. 

steel  of  recent,  65. 

testing  of,  318. 
Prime  movers,  222. 

size  of,  224. 

tests  of,  325. 

Pumping  machinery,  262. 
Pumps,  air,  266. 

boiler  feed,  268. 

circulating  water,  264. 

fire,  268. 

house,  266. 

hot  well,  266. 

oil,  268,  271. 

steam  or  electric  drive,  262. 
Purifier,  Dervaux-Reisert,  150. 

Q. 

Quadruple  expansion  engines,  230. 

R. 

Radial  brick  chimneys,  136. 

Reciprocating  engine,  classification  of,  225. 

Reciprocating  engines,  225. 

Reinforced  concrete  chimneys,  140. 

Reisert  purifier,  150. 

Roof  construction,  structural  steel,  58,  59. 

leaders,  structural  steel,  59. 
Runway,  crane,  61. 

S. 

Safety  of  boilers,  86. 
Sarco  CO2  recorder,  116. 
Saturated  steam,  175. 
jScreens,  area  of,  39. 
Setting  of  boilers,  91. 
Shut-off  gates,  condenser  water,  39. 
Site,  selection  of,  41. 
Small  plants,  design  of,  292. 
Smoke  flue,  59th  Street,  New  York,  354. 
Smoke  flues,  131. 

character  of,  131. 

dampers,  133. 

doors,  133. 


Smoke  flues  —  continued. 

expansion  joints,  132. 

leakage  of,  133. 

shape  of,  131. 

size  of,  131. 
Soil,  bearing  power  of,  44. 

character  of,  12,  41. 

test  holes,  41. 

Spontaneous  combustion,  29. 
St.  Denis  Plant,  Paris,  336. 

auxiliary  electrical  equipment,  346. 

boiler  room,  341. 

coal  and  ash  handling  systems,  340. 

condenser  plant,  344. 

dimensions  and  data,  423. 

feed-water  plant,  342. 

layout,  336. 

operating  force,  349. 

switching  room,  348. 

turbo-generator,  343. 
Stairways,  56. 
Steam  blowers,  130. 
Steam,  saturated,  175. 

superheated,  175. 

consumption  of  auxiliaries,  263. 

or  electric  driven  pumps,  262. 
Steel  chimneys,  142. 
Steel,  structural,  59. 
Stokers,  mechanical,  99. 
Storage  battery,  290. 
Storage  of  boiler  feed-water,  150. 

of  coal,  27. 
Structural  steel,  59. 

building  framing,  61. 

building  material,  61. 

character  of,  68. 

crane  runway,  61. 

expansion  joints,  64. 

fiber  stresses,  64. 

floor  loads,  63. 

frame  insulation,  68. 

inspection,  66. 

of  plants,  65. 

painting,  66. 

roof,  58. 

roof  construction,  59. 

roof  leaders,  59. 


INDEX. 


455 


Structural  steel  —  continued. 

types  of  columns,  62. 

workmanship,  65. 

Substructure,  Chelsea  Plant,  London,  361. 
Superheated  steam,  175. 
Superheaters,  163. 

circulation  of  steam,  166. 

classification,  163. 

controlling  temperature,  167. 

cross-section,  164. 

flow  of  gases,  166. 

material  of,  163. 

size  of,  172. 

types  of,  173. 

velocity  of  steam  in,  171. 
Supports,  pipe,  190. 
Surface  condenser,  248. 
Switches,  oil,  285. 
Switchboards,  288. 

architectural  features,  80. 

gallery,  52. 

Twin  Municipal  Plant,  Vienna,  394. 
Switching  room,  25,  278. 

Chelsea  Plant,  London,  369. 

Fisk  Street  Plant,  Chicago,  380. 

St.  Denis  Plant,  Paris,  348. 

T. 

Test  holes,  soil,  41. 

Test,  Twin  Municipal  Plant,  Vienna,  397. 

Tests  of  boilers,  318. 

of  engine,  325. 

of  generator,  333. 

of  piles,  44. 

of  prime  movers,  325. 

of  turbines,  327. 
Testing  power  plants,  318. 
Toilets,  56. 

Trenches,  pipe,  51,  78. 
Trimming  of  boilers,  92. 
Tunnels,  area  of  condenser  water,  39. 

arrangement  of  condenser  water,  39. 

condenser  water,  38. 
Turbine  tests,  327. 

Turbine  and  engine,  comparison,  222. 
Turbines,  231. 

classification  of,  231. 


Turbines  —  continued. 

compound  impulse,  233. 

reaction,  238. 

single  impulse,  232. 
Turbo-generators,  Chelsea  Plant,  London,  366. 

59th  Street  Plant,  New  York,  359. 

Fisk  Street  Plant,  Chicago,  374. 

St.  Denis  Plant,  Paris,  343. 
Twin  Municipal  Plant,  Vienna,  381. 

boiler  feed-water  supply,  387. 

boiler  room,  387. 

chimneys,  392. 

coal  handling  system,  384. 

condenser  water  supply,  384. 

crane,  394. 

engines,  392. 

exciters,  394. 

generators,  393. 

steam  piping,  392. 

switchboard,  394. 

tests,  397. 

U. 

Underfeed  stoker,  102. 
Unit  system,  complete,  17. 

V. 

Vacuum  breaker,  252. 
Vacuum  piping,  220. 
Valves,  206. 
Ventilation,  53. 

Volume  of  power  houses  per  K.W.  capacity, 
436- 

W. 

Walls,  52. 

architectural  features  of,  78. 
Water  circulation  in  boilers,  88. 
Water  purifier,  150. 
Water  required,  condenser,  244. 
Water  supply,  n. 

condenser,  38. 

Waterproofing  of  foundations,  48. 
Weight  of  masonry,  46. 
Windows,  52. 

architectural  features,  76. 
Wiring  diagrams,  282. 


LIST    OF    WORKS 


ON 


ELECTRICAL   SCIENCE 

PUBLISHED    AND    FOR    SALE    BY 

D.  VAN  NOSTRAND  COMPANY, 

23  Murray  and  27  Warren  Streets,  New  York. 


ABBOTT,  A.  V.  The  Electrical  Transmission  of  Energy.  A  Manual  for  the 
Design  of  Electrical  Circuits.  Fifth  Edition,  revised  and  rewritten.  With 
many  Diagrams  and  Engravings  and  Folding  Plates.  8vo,  cloth.  Net,  $5.00. 

ANDERSON,  GEO.  L.,  A.M.  (Capt.  U.S.A.).  Handbook  for  the  Use  of  Electricians 
in  the  operation  and  care  of  Electrical  Machinery  and  Apparatus  of  the 
United  States  Seacoast  Defenses.  Prepared  under  the  direction  of  Lieut.- 
General  Commanding  the  Army.  Illustrated.  8vo,  cloth.  $3.00. 

ARNOLD,  E.  Armature  Windings  of  Direct-Current  Dynamos.  Extension  and 
Application  of  a  general  Winding  Rule.  Translated  from  the  original  German 
by  Francis  B.  DeGress,  M.E.  Illustrated.  8vo,  cloth.  $2.00. 

ASHE,  S.  W.,  and  KEILEY,  J.  D.  Electric  Railways,  Theoretically  and  Practically 
Treated — Rolling  Stock.  With  Diagrams  and  Folding  Plates.  12mo,  cloth, 
290  pp.  Illustrated.  Net,  $2.50. 

Vol.  II.    Engineering  Preliminaries,  Substations,  and    the    Distributing    System. 
12T10,  cloth.     Illustrated.     282pp.     Net,  $2.50. 

ATKINSON,  A.  A.,  Prof.  (Ohio  Univ.).  Electrical  and  Magnetic  Calculations.  For 
the  use  of  Electrical  Engineers  and  others  interested  in  the  Theory  and 
Application  of  Electricity  and  Magnetism.  Second  Edition,  revised.  Illus- 
trated. 8vo,  cloth.  Net,  $1.50. 

ATKINSON,  PHILIP.  The  Elements  of  Dynamic  Electricity  and  Magnetism. 
Fourth  Edition.  Illustrated.  8vo,  cloth.  $2.00. 

Elements  of  Electric  Lighting,  including  Electric  Generation,  Measurement, 

Storage,  and  Distribution.  Tenth  ,Edition,  fully  revised  and  new  matter 
added.  Illustrated.  8vo,  cloth.  $1.50. 

Power  Transmitted  by  Electricity  and  Applied  by  the  Electric  Motor,  including 

Electric  Railway  Construction.  Illustrated.  Fourth  Edition,  fully  revised 
and  new  matter  added.  8vo,  cloth.  $2.00- 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

AYRTON,  HERTHA.     The  Electric  Arc.     8vo,  cloth.     Illustrated.     479  pp.     Net, 

$5.00. 
BIGGS,   C.   H.   W.     First   Principles   of  Electricity   and  Magnetism.     Illustrated. 

12mo,  cloth.     $2.00. 

BLAKESLEY,  T.  H.  Papers  on  Alternating  Currents  of  Electricity.  For  the  use 
of  Students  and  Engineers.  Third  Edition,  enlarged.  12mo,  cloth.  $1.50. 

BOTTONE,  S.  R.     Electric  Bells  and  All  about  Them.     12mo,  cloth.     50  cents. 

—  Electrical    Instrument-Making    for  Amateurs.     A  Practical  Handbook.     En- 

larged by  a  chapter  on  "The  Telephone."     Sixth  Edition.     With  48  Illus- 
trations.    12mo,  cloth.     50  cents. 

—  Electric  Motors,  How  Made  and  How  Used.     12mo,  cloth.     75  cents. 

BOWKER,  WM.  R.  Dynamo,  Motor,  and  Switchboard  Circuits  for  Electrical 
Engineers:  a  practical  book  dealing  with  the  subject  of  Direct,  Alternating 
and  Polyphase  Currents.  With  over  100  Diagrams  and  Engravings.  8vo, 
cloth.  Illustrated.  Net,  $2.25. 

CHILD,  CHAS.  T.  The  How  and  Why  of  Electricity:  a  book  of  information  for 
non-technical  readers,  treating  of  the  properties  of  Electricity,  and  how 
it  is  generated,  handled,  controlled,  measured,  and  set  to  work.  Also 
explaining  the  operation  of  Electrical  Apparatus.  8vo,  cloth.  Illustrated. 
$1.00. 

COOPER,  W.  R.  Primary  Batteries:  their  Theory,  Construction,  and  Use.  8vo, 
cloth,  324  pp.  131  Illustrations.  Net,  $4.00. 

CROCKER,  F.  B.,  and  WHEELER,  S.  S.  The  Management  of  Electrical  Ma- 
chinery. Being  a  thoroughly  revised  and  rewritten  edition  of  the  authors' 
"  Practical  Management  of  Dynamos  and  Motors."  12mo,  cloth,  223 
pp.  Illustrated.  Net,  $1.00. 

CROCKER,  F.  B.  Electric  Lighting.  A  Practical  Exposition  of  the  Art  for  the 
use  of  Electricians,  Students,  and  others  interested  in  the  Installation  or 
Operation  of  Electric-Lighting  Plants.  Volume  I.:  The  Generating  Plant. 
Seventh  Edition,  entirely  revised.  8 vo,  cloth.  $3.00.  Volume  II.:  Distrib- 
uting System  and  Lamps.  Sixth  Edition.  8vo,  cloth.  Each,  $3.00. 

DESMOND,  CHAS.  Electricity  for  Engineers.  Part  I.:  Constant  Current.  Part 
II.:  Alternate  Current.  Revised  Edition.  Illustrated.  12mo,  cloth.  $2.50. 

DIBDIN,  W.  J.  Public  Lighting  by  Gas  and  Electricity.  With  many  Tables, 
Figures,  and  Diagrams.  8vo,  cloth.  Illustrated.  537  pp.  $8.50. 

DYNAMIC  ELECTRICITY;  Its  Modern  Use  and  Measurement,  chiefly  in  its  appli- 
cation to  Electric  Lighting  and  Telegraphy,  including:  1.  Some  Points  in 
Electric  Lighting,  by  Dr.  John  Hopkinson.  2.  On  the  Treatment  of  Elec- 
tricity for  Commercial  Purposes,  by  J.  N.  Shoolbred.  3.  Electric-Light 
Arithmetic,  by  R.  E.  Day,  M.E.  18mo,  boards.  (No.  71  Van  Nostrand's 
Science  Series.)  50  cents. 

EWING,  J.  A.  Magnetic  Induction  in  Iron  and  other  Metals.  Third  Edition,  re- 
vised. Illustrated.  8vo,  cloth.  $4.00. 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

FISHER,  H.  K.  C.,  and  DARBY,  W.  C.     Students  Guide  to  Submarine  Cable  Testing. 

Third  Edition,  new,  enlarged.     8vo,  cloth.     Illustrated.     Net,  $3.50. 

FISHER,  W.  C.     The  Potentiometer  and  Its  Adjuncts.     8vo,  cloth.     Net,  $2.25. 

FLEMING,  J.  A.,  Prof.  The  Alternate-Current  Transformer  in  Theory  and  Prac- 
tice. Vol.  I.:  The  Induction  of  Electric  Currents.  500  pp.  Fifth  Issue. 
Illustrated.  8vo,  cloth.  $5.00.  Vol.  II.:  The  Utilization  of  Induced 
Currents.  Third  Issue.  594  pp.  Illustrated.  8vo,  cloth.  $5.00. 

Electric  Lamps  and  Electric  Lighting.     8vo,  cloth.     $2.50. 

A  Handbook  for  the  Electrical  Laboratory  and  Testing-room.  2  vols.  8vo, 

cloth.  Each,  $5.00. 

FOSTER,  H.  A.  Electrical  Engineers'  Pocket  Book.  With  the  Collaboration  of 
Eminent  Specialicts.  A  handbook  of  useful  data  for  Electricians  and 
Electrical  Engineers.  With  innumerable  Tables,  Diagrams,  and  Figures. 
The  most  complete  book  of  its  kind  ever  published,  treating  of  the  latest 
and  best  Practice  in  Electrical  Engineering.  Fifth  Edition,  revised.  Pocket 
size,  full  leather,  1150  pp.  Thumb  index.  $5.00. 

GERHARDI,  C.  H.  W.  Electricity  Meters.  8vo,  cloth,  337  pp.  220  Illustra- 
tions. Net,  $4.00. 

GORE,  GEORGE,  Dr.  The  Art  of  Electrolytic  Separation  of  Metals  (Theoretical 
and  Practical).  Illustrated.  8vo,  cloth.  $3.50. 

GRAY,  J.  Electrical  Influence  Machines:  Their  Historical  Development  and 
Modern  Forms.  With  Instructions  for  making  them.  Second  Edition, 
revised  and  enlarged.  With  105  Figures  and  Diagrams.  12mo,  cloth.  Illus- 
trated. $2.00. 

HAMMER,  W.  J.  Radium,  and  Other  Radio-active  Substances;  Polonium,  Actin- 
ium, and  Thorium.  With  a  consideration  of  Phosphorescent  and  Fluo- 
rescent Substances,  the  properties  and  applications  of  Selenium,  and  the 
treatment  of  disease  by  the  Ultra-Violet  Light.  With  Engravings  and 
Plates.  8vo,  cloth.  Illustrated.  $1.00. 

HASKINS,  C.  H.  The  Galvanometer  and  its  Uses.  A  Manual  for  Electricians 
and  Students.  Fourth  Edition,  revised.  12mo,  morocco.  $1.50. 

—  Transformers:  Their  Theory,  Construction,  and  Application  Simplified.     Illus- 

trated.    12mo,  cloth.     $1.25. 

HAY,  A.  Alternating  Currents:  Their  Theory,  Generation,  and  Transformation. 
8vo,  cloth.  Illustrated.  Net,  $2.50. 

—  Introductory  Course   of   Continuous-Current   Engineering.      8vo,  cloth,  327 

pp.     183  Illustrations.     Net,  $2.50. 

HEAVISIDE,  0.     Electromagnetic  Theory.     Svo,  cloth.     2  vols.     Each,  $5.00. 
HOBBS,  W.  R.  P.     The  Arithmetic  of  Electrical  Measurements.     With  numerous 

examples,  fully  worked.     Ninth  Edition.     12mo,  cloth.     50  cents. 
HOPKINS,  N.  M.      Experimental    Electrochemistry,  Theoretically    and    Practically 

Treated.      Profusely    illustrated    with    130   new  drawings,    diagrams,    and 

photographs,  accompanied  by   a   Bibliography.     Svo,    cloth.     Illustrated. 

284  pages.     Net,  $3.00.     • 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

HUTCHINSON,  R.  W.,  Jr.  Long-Distance  Electric  Power  Transmission:  Being  a 
Treatise  on  the  Hydro-Electric  Generation  of  Energy;  Its  Transformation, 
Transmission,  and  Distribution.  12mo,  cloth,  344  pp.  Illus.  Net,  $3.00. 

INCANDESCENT  ELECTRIC  LIGHTING.  A  Practical  Description  of  the  Edison 
System,  by  H.  Latimer.  To  which  is  added:  The  Design  and  Operation  of 
Incandescent  Stations,  by  C.  J.  Field:  A  Description  of  the  Edison  Electro- 
lyte Meter,  by  A.  E.  Kennelly;  and  a  Paper  on  the  Maximum  Efficiency  of 
Incandescent  Lamps,  by  T.  W.  Howell.  Illustrated.  16mo,  cloth.  (No. 
57  Van  Nostrand's  Science  Series.)  50  cents. 

INDUCTION  COILS:  How  Made  and  How  Used.  Third  Edition.  16mo,  cloth. 
(No.  53  Van  Nostrand's  Science  Series.)  50  cents. 

JEHL,  FRANCIS,  Member  A.I.E.E.  The  Manufacture  of  Carbons  for  Electric 
Lighting  and  other  purposes.  Illustrated  with  numerous  Diagrams,  Tables, 
and  Folding  Plates.  Illustrated.  8vo,  cloth.  $4.00. 

JONES,  HARRY  C.  Electrical  Nature  of  Matter  and  Radioactivity.  12mo,  cloth. 
$2.00. 

KAPP,  GISBERT,  C.  E.  Electric  Transmission  of  Energy  and  its  Transformation, 
Subdivision,  and  Distribution.  A  Practical  Handbook.  Fourth  Edition, 
thoroughly  revised.  12mo,  cloth.  $3.50. 

—  Alternate-Current  Machinery.     190  pp.     Illustrated.     (No.  96  Van  Nostrand's 

Science  Series.)     50  cents. 

KELSEY,  W.  R.  Continuous-Current  Dynamos  and  Motors,  and  their  Control; 
being  a  series  of  articles  reprinted  from  the  "Practical  Engineer,"  and  com- 
pleted by  W.  R.  Kelsey,  B.Sc.  With  Tables,  Figures,  and  Diagrams.  8vo, 
cloth.  Illustrated.  $2.50. 

KEMPE,  H.  R.  A  Handbook  of  Electrical  Testing.  Fifth  Edition.  200  Illus- 
trations. 8vo,  cloth.  $6.00. 

KENNEDY,  R.  Modern  Engines  and  Power  Generators.  4to,  cloth.  Illustrated. 
6  vols.  Each,  $3.50.  Complete  set,  $15.00. 

—  Electrical  Installations  of  Electric  Light,  Power,  and  Traction  Machinery.  5  vols. 

8vo,  cloth.     Illustrated.     Each,  $3.50.       Complete  set,  $15.00. 

KENNELLY,  A.  E.  Theoretical  Elements  of  Electro-Dynamic  Machinery.  Vol.  I. 
Illustrated.  8vo,  cloth.  $1.50. 

KINZBRUNNER,  C.  Continuous-Current  Armatures:  Their  Winding  and  Con- 
struction. 8vo,  cloth,  SO  pp.  79  Illustrations.  Net,  $1.50. 

—  Alternate-Current  Windings:  Their  Theory  and  Construction.      8vo,  cloth, 

80pp.     89  Illustrations.     Net,  $1.50. 

LIVERMORE,  V.  P.,  and  WILLIAMS,  J.  How  to  Become  a  Competent  Motorman: 
being  a  practical  treatise  on  the  proper  method  of  operating  a  street-railway 
motor-car;  also  giving  details  how  to  overcome  certain  defects.  16mo, 
cloth.  Illustrated.  Revised  Edition.  In  Press. 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

LOCKWOOD,  T.  D.  Electricity,  Magnetism,  and  Electro-Telegraphy.  A  Prac- 
tical Guide  and  Handbook  of  General  Information  for  Electrical  Students, 
Operators,  and  Inspectors.  Fourth  Edition.  Illustrated.  8vo,  cloth. 
$2.50 

LORING,  A.  E.  A  Handbook  of  the  Electro-Magnetic  Telegraph.  Fourth  Edition, 
revised.  16mo,  cloth.  (No.  39  Van  Nostrand's  Science  Series.)  50  cents. 

LUPTON,  A.  PARR,  G.  D.  A.,  and  PERKIN,  H.  Electricity  Applied  to  Mining. 
With  Tables,  Diagrams,  and  Folding  Plates.  Second  Edition,  revised  and 
enlarged.  8vo,  cloth,  280  pp.  Illustrated.  Net,  $4.50. 

MANSFIELD,  A.  N.  Electromagnets:  Their  Design  and  Construction.  (No.  64 
Van  Nostrand's  Science  Series.)  50  cents. 

MURRAY,  JAS.  ERSKINE.  A  Handbo  k  of  Wireless  Telegraphy :  Its  Theory  and 
Practice.  8vo,  cloth,  320  pp.  Illustrated.  Net,  $3.50. 

NIPHER,  FRANCIS  E.,  A.M.  Theory  of  Magnetic  Measurements.  With  an 
Appendix  on  the  Method  of  Least  Squares.  12mo,  cloth.  $1.00. 

OHM,  G.  S.,  Dr.  The  Galvanic  Circuit  Investigated  Mathematically.  Berlin, 
1827.  Translated  by  William  Francis.  With  Preface  and  Notes  by  the 
Editor,  Thos.  D.  Lockwood.  12mo,  cloth.  (No.  102  Van  Nostrand's 
Science  Series.)  50  cents. 

OUDIN,  MAURICE,  A.  M.  S.  Standard  Polyphase  Apparatus  and  Systems.  Illus- 
trated, with  many  Photo-reproductions,  Diagrams,  and  Tables.  Fifth 
Edition,  revised.  8vo,  cloth.  $3.00. 

PALAZ,  A.  Treatise  on  Industrial  Photometry.  Specially  applied  to  Electric 
Lighting.  Translated  from  the  French  by  G.  W.  Patterson,  Jr.,  Assistant 
Professor  of  Physics  in  the  University  of  Michigan,  and  M.  R.  Patterson,  B.A. 
Second  Edition.  Fully  Illustrated.  8vo,  cloth.  $4.00. 

PARSHALL,  H.  F.,  and  HOBART,  H.  M.  Armature  Windings  of  Electric  Machines. 
Third  Edition.  With  140  full-page  Plates,  65  Tables,  and  descriptive 
letter-press.  4to,  cloth.  $7.50. 

—  Electric  Railway  Engineering.      4to,  cloth.      Illustrated  with  many  Diagrams 
and  Plates.     Net,  $10.00. 

PERRINE,  F.  A.  C.,  A.M.,  D.Sc.  Conductors  for  Electrical  Distribution:  Their 
Manufacture  and  Materials,  the  Calculation  of  Circuits,  Pole-Line  Construc- 
tion, Underground  Working,  and  other  Uses.  Second  Edition,  revised. 
8vo,  cloth.  Illustrated.  Net,  $3.50. 

PLANTE,  GASTON.  The  Storage  of  Electrical  Energy,  and  Researches  in  the 
Effects  created  by  Currents  combining  Quantity  with  High  Tension.  Trans- 
lated from  the  French  by  Paul  B.  Elwell.  89  Illustrations.  8vo.  $4.00. 


LIST  OF  WORKS  ON  ELECTRICAL  SCIENCE. 

POPE,  F.  L.  Modern  Practice  of  the  Electric  Telegraph.  A  Handbook  for  Elec- 
tricians and  Operators.  An  entirely  new  work,  revised  and  enlarged,  and 
brought  up  to  date  throughout.  Illustrations.  8vo,  cloth.  $1.50. 

RAPHAEL,  F.  C.  Localization  of  Faults  in  Electric-Light  Mains.  Second  Edition, 
revised.  8vo,  cloth.  Illustrated.  Net,  $3.00. 

RAYMOND,  E.  B.  Alternating-Current  Engineering,  Practically  Treated.  With 
many  P'igures  and  Diagrams.  Third  Edition,  revised.  8vo,  cloth.  Illus- 
trated. Net,  $2.50. 

RUHMER,  E.  Wireless  Telephony:  Its  Theory  and  Practice.  Translated  from 
the  German  by  Jas.  Erskine  Murray.  8vo,  cloth,  224  pp.  143  Illustra- 
tions. Net,  $3.50. 

SALOMONS,  Sir  DAVID,  M.A.  Electric-Light  Installations.  A  Practical  Hand- 
book. Seventh  Edition,  revised  and  enlarged.  Vol.  I.:  Management  of 
Accumulators.  Illustrated.  12mo,  cloth,  178  pp.  Ninth  Edition,  revised. 
Net,  $2.50.  Vol.11.:  Apparatus.  Illustrated.  12mo,  cloth.  $2.25.  Vol. 
III.:  Application.  Illustrated.  12mo,  cloth.  $1.50. 

SEVER,  G.  F.  Electrical  Engineering  Experiments  and  Tests  on  Direct-Current 
Machinery.  With  Diagrams  and  Figures.  Second  Edition.  8vo,  pamphlet. 
Illustrated.  Net,  $1.00. 

SEVER,  G.  F.,  and  TOWNSEND,  F.  Laboratory  and  Factory  Tests  in  Electrical 
Engineering.  Second  Edition,  thoroughly  revised  and  enlarged.  8vo, 
cloth.  Illustrated.  225  pp.  Net,  $2.50. 

SEWALL,  C.  H.  Wireless  Telegraphy.  With  Diagrams  and  Figures.  Second 
Edition,  corrected.  8vo,  cloth.  Illustrated.  Net,  $2.00. 

—  Lessons  in  Telegraphy.     12mo,  cloth.     Illustrated.     In  Press. 


SEWELL,  T.  Elements  of  Electrical  Engineering.  Second  Edition,  revised. 
8vo,  cloth.  Illustrated.  432  pp.  Net,  $3.00. 

The  Construction  of  Dynamos.       8vo,    cloth,    316  pp.       With  250   Special 

Engravings  and  Diagrams.     Net,  $3.00. 

SHELDON,  S.,  Ph.D.,  and  MASON,  H.,  B.S.  Dynamo-Electric  Machinery:  Its 
Construction,  Design,  and  Operation.  Direct-Current  Machines.  Sixth 
Edition,  revised.  Illustrated.  8vo,  cloth.  Net,  $2.50. 

—  Alternating-Current  Machines:  being  the  second  volume  of  the  authors'  "Dy- 
namo-Electric Machinery:  its  Construction,  Design,  and  Operation."  With 
many  Diagrams. and  Figures.  (Binding  uniform  with  Volume  I.)  Fifth 
Edition.  Illustrated.  8vo,  cloth.  Net,  $2.50. 


LIST  OF   WORKS  ON  ELECTRICAL  SCIENCE. 

SNELL,  ALBION  T.  Electric  Motive  Power.  The  Transmission  and  Distribution 
of  Electric  Power  by  Continuous  and  Alternating  Currents.  With  a  Section 
on  the  Applications  of  Electricity  to  Mining  Work.  Second  Edition,  revised. 
Illustrated.  8vo,  cloth.  $4.00. 

SODDY,  F.  Radio-activity:  an  Elementary  Treatise  from  the  Standpoint  of  the 
Disintegration  Theory.  Fully  Illustrated,  and  with  a  complete  table  of 
Contents  and  Extended  Index.  8vo,  cloth.  Illustrated.  Net,  $3.00. 

SWINBURNE,  JAS.,  and  WORDINGHAM,  C.  H.  The  Measurement  of  Electric 
Currents.  Electrical  Measuring  Instruments.  Meters  for  Electrical  Energy. 
Edited,  with  Preface,  by  T.  Commerford  Martin.  Folding  Plate  and  numer- 
ous Illustrations.  16mo,  cloth.  50  cents. 

SWOOPE,  C.  WALTON.  Practical  Lessons  in  Electricity:  Principles,  Experi- 
ments, and  Arithmetical  Problems.  An  Elementary  Text-book.  With 
numerous  Tables,  Formulae,  and  two  large  Instruction  Plates.  Ninth 
Edition,  Twelfth  Thousand.  Illustrated.  8vo,  cloth.  Net,  $2.00. 

THOM,  C.,  and  JONES,  W.  H.  Telegraphic  Connections,  embracing  recent  methods 
in  Quadruplex  Telegraphy.  20  Colored  Plates.  8vo,  cloth.  $1.50. 

THOMPSON,  S.  P.,  Prof.  Dynamo-Electric  Machinery.  With  an  Introduction 
and  Notes  by  Frank  L.  Pope  and  H.  II.  Butler.  Fully  Illustrated.  (No.  66 
Van  Nostrand's  Science  Series.)  50  cents. 

—  Recent    Progress    in    Dynamo-Electric    Machines.     Being  a  Supplement  to 

"Dynamo-Electric   Machinery."     Illustrated.     12mo,   cloth.     (No.   75  Van 
Nostrand's  Science  Series.)     50  cents. 

—  Dynamo-Electric  Machinery.     Vol.  I.     8vo,  cloth,  996  pp.     573  Illustrations. 

4  Colored  and  32  Folding  Plates.     $7.50. 

-  Vol.  II.     Alternating-Current   Machines.      848   pp.      546   Illustrations.      15 
Colored  Plates,  24  Folding  Plates.     8vo,  cloth.     $7.50. 

TUNZELMANN,  G.  W.  de.     Electricity  in  Modern  Life.     Illustrated.     12mo,  cloth. 

$1.25. 

UNDERBILL,  C.  R.  The  Electromagnet:  Being  a  new  and  revised  edition  of 
"The  Electromagnet,"  by  Townsend  Walcott,  A.  E.  Kennelly,  and  Richard 
Varley.  With  Tables  and  Numerous  Figures  and  Diagrams.  12mo,  cloth. 
Illustrated  $1.50. 

URQUHART,  J.  W.  Dynamo  Construction.  A  Practical  Handbook  for  the  use 
of  Engineer  Constructors  and  Electricians  in  Charge.  Illustrated.  12mo, 
cloth  $3.00. 


LI  XT  OF   WORKS  ON  ELECTRICAL  SCIENCE. 

URQUHART,  J.  W .  Electric  Ship-Lighting.  A  Handbook  on  the  Practical  Fit- 
ting and  Running  of  Ship's  Electrical  Plant,  for  the  use  of  Ship  Owners 
and  Builders,  Marine  Electricians,  and  Sea-going  Engineers  in  Charge.  88 
Illustrations.  12mo,  cloth.  $3.00. 

• Electric-Light  Fitting.  A  Handbook  for  Working  Electrical  Engineers,  em- 
bodying Practical  Notes  on  Installation  Management.  Second  Edition,  with 
additional  chapters.  With  numerous  Illustrations.  12mo,  cloth.  $2.00. 

—  Electroplating.     Fourth  Edition.     12mo,  cloth.     $2.00. 
-  Electrotyping.      12mo,  cloth.     $2.00. 

WADE,  E.  J.  Secondary  Batteries:  Their  Theory,  Construction,  and  Use.  With 
innumerable  Diagrams  and  Figures.  8vo,  cloth.  Illustrated.  Net,  $4.00. 

WALKER,  FREDERICK.  Practical  Dynamo-Building  for  Amateurs.  How  to 
Wind  for  any  Output.  Illustrated.  16mo,  cloth.  (No.  98  Van  Nostrand's 
Science  Series.)  50  cents. 

WALKER,  S.  F.  Electricity  in  Our  Homes  and  Workshops.  Fourth  Edition,  re- 
vised and  enlarged.  12mo,  cloth,  359  pp.  205  Illustrations.  Net,  $2.00. 

—  Electricity   in   Mining.      With  Figures,   Diagrams,   and   Plates.      8vo,  cloth. 

Illustrated.     385  pp.     Net,  $3.50. 

WALLING,  B.  T.,  Lieut.-Com.  U.S.N.,  and  MARTIN,  JULIUS.  Electrical  Installa- 
tions of  the  United  States  Navy.  With  many  Diagrams  and  Engravings. 
8vo.  648  pp.  300  Illustrations.  Net,  $6.00. 

WATT.     Electroplating  and   Refining   of   Metals.     8vo,    cloth.      Illustrated.     Net 

$4.50. 

—  Electro-Metallurgy.     Eleventh  Edition.     12mo,  cloth.     $1.00. 

WEBB,  H.  L.  A  Practical  Guide  to  the  Testing  of  Insulated  Wires  and  Cables. 
Illustrated.  12mo,  cloth.  $1.00. 

WEEKS,  R.  W.  The  Design  of  Alternate-Current  Transformer.  New  Edition. 
In  press. 

WEYMOUTH,  F.  MARTEN.  Drum  Armatures  and  Commutators.  (Theory  and 
Practice.)  A  complete  treatise  on  the  theory  and  construction  of  drum- 
winding,  and  of  commutators  for  closed-coil  armatures,  together  with  a  full 
r6sum£  of  some  of  the  principal  points  involved  in  their  design;  and  an 
exposition  of  armature  reactions  and  sparking.  Illustrated.  8vo,  cloth. 
$3.00. 

WILKINSON,  H.  D.  Submarine  Cable-Laying,  Repairing,  and  Testing.  8vo, 
cloth.  Reprinting. 


THIS  BOOK  IS  DUE  ON  THE  LAST  DATE 
STAMPED  BELOW 


AN  INITIAL  FINE  OF  25  CENTS 

WILL  BE  ASSESSED  FOR  FAILURE  TO  RETURN 
THIS  BOOK  ON  THE  DATE  DUE.  THE  PENALTY 
WILL  INCREASE  TO  SO  CENTS  ON  THE  FOURTH 
DAY  AND  TO  $1.OO  ON  THE  SEVENTH  DAY 
OVERDUE. 


$IV    aw  i 

* 

nrr>    n«J  ItHQ 

DEC    8EB   '^ 

A  nn   ^   o  on 

APR  1  8  W 

LD  21-100m-8,'34 

U' 
196446 


,V|..^ 


